Merge with default

docs/dtd/plugin/2.0.0-01.dtd

@@ -23,7 +23,7 @@
 -->
 
 <!--- root element of the plugin descriptor -->
-<!ELEMENT plugin (scm-version|information|child-first-classloader|conditions|resources|dependencies|extension|extension-point|rest-resource|subscriber)*>
+<!ELEMENT plugin (scm-version|information|child-first-classloader|conditions|resources|dependencies|optional-dependencies|extension|extension-point|rest-resource|subscriber)*>
 
 <!--- major scm-manager version -->
 <!ELEMENT scm-version (#PCDATA)>
@@ -79,13 +79,19 @@
 <!--- contains plugin dependencies -->
 <!ELEMENT dependencies (dependency)*>
 
-<!--- sing plugin dependency -->
+<!--- contains optional plugin dependencies -->
+<!ELEMENT optional-dependencies (dependency)*>
+
+<!--- single plugin dependency -->
 <!ELEMENT dependency (#PCDATA)>
 
 <!-- generated entries -->
 
 <!--- extension -->
-<!ELEMENT extension (description|class)*>
+<!ELEMENT extension (description|class|requires)*>
+
+<!--- requires value -->
+<!ELEMENT requires (#PCDATA)>
 
 <!--- class value -->
 <!ELEMENT class (#PCDATA)>

package.json

@@ -20,7 +20,7 @@
   },
   "resolutions": {
     "babel-core": "7.0.0-bridge.0",
-    "gitdiff-parser": "https://github.com/scm-manager/gitdiff-parser#6baa7278824ecd17a199d842ca720d0453f68982"
+    "gitdiff-parser": "https://github.com/scm-manager/gitdiff-parser#ed3fe7de73dbb0a06c3e6adbbdf22dbae6e66351"
   },
   "babel": {
     "presets": [

pom.xml

@@ -284,6 +284,12 @@
         <version>${jackson.version}</version>
       </dependency>
 
+      <dependency>
+        <groupId>org.hibernate</groupId>
+        <artifactId>hibernate-validator</artifactId>
+	<version>${hibernate-validator.version}</version>
+      </dependency>
+
       <!-- JUnit 5 -->
 
       <dependency>
@@ -843,6 +849,7 @@
     <jackson.version>2.10.0</jackson.version>
     <guice.version>4.0</guice.version>
     <jaxb.version>2.3.0</jaxb.version>
+    <hibernate-validator.version>6.1.0.Final</hibernate-validator.version>
 
     <!-- event bus -->
     <legman.version>1.6.1</legman.version>

scm-annotations/src/main/java/sonia/scm/plugin/Extension.java

@@ -49,4 +49,15 @@ import java.lang.annotation.Target;
 @Target({ ElementType.TYPE })
 @PluginAnnotation("extension")
 @Retention(RetentionPolicy.RUNTIME)
-public @interface Extension {}
+public @interface Extension {
+  /**
+   * This extension is loaded only if all of the specified plugins are installed.
+   * The requires attribute can be used to implement optional extensions.
+   * A plugin author is able to implement an extension point of an optional plugin and the extension is only loaded if
+   * all of the specified plugins are installed.
+   *
+   * @since 2.0.0
+   * @return list of required plugins to load this extension
+   */
+  String[] requires() default {};
+}

scm-core/pom.xml

@@ -173,6 +173,13 @@
       <artifactId>activation</artifactId>
     </dependency>
 
+    <!-- validation -->
+
+    <dependency>
+      <groupId>org.hibernate</groupId>
+      <artifactId>hibernate-validator</artifactId>
+    </dependency>
+
     <!-- util -->
 
     <dependency>
@@ -214,12 +221,6 @@
       <artifactId>shiro-unit</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.hibernate</groupId>
-      <artifactId>hibernate-validator</artifactId>
-      <version>5.3.6.Final</version>
-      <scope>compile</scope>
-    </dependency>
 
   </dependencies>
 

scm-core/src/main/java/sonia/scm/plugin/ExtensionElement.java

@@ -0,0 +1,26 @@
+package sonia.scm.plugin;
+
+import lombok.AllArgsConstructor;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import java.util.HashSet;
+import java.util.Set;
+
+@Getter
+@ToString
+@NoArgsConstructor
+@EqualsAndHashCode
+@AllArgsConstructor
+@XmlAccessorType(XmlAccessType.FIELD)
+public class ExtensionElement {
+  @XmlElement(name = "class")
+  private String clazz;
+  private String description;
+  private Set<String> requires = new HashSet<>();
+}

scm-core/src/main/java/sonia/scm/plugin/InstalledPluginDescriptor.java

@@ -38,6 +38,7 @@ package sonia.scm.plugin;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
@@ -76,7 +77,7 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
    */
   public InstalledPluginDescriptor(int scmVersion, PluginInformation information,
                                    PluginResources resources, PluginCondition condition,
-                                   boolean childFirstClassLoader, Set<String> dependencies)
+                                   boolean childFirstClassLoader, Set<String> dependencies, Set<String> optionalDependencies)
   {
     this.scmVersion = scmVersion;
     this.information = information;
@@ -84,6 +85,7 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
     this.condition = condition;
     this.childFirstClassLoader = childFirstClassLoader;
     this.dependencies = dependencies;
+    this.optionalDependencies = optionalDependencies;
   }
 
   //~--- methods --------------------------------------------------------------
@@ -116,7 +118,8 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
       && Objects.equal(information, other.information)
       && Objects.equal(resources, other.resources)
       && Objects.equal(childFirstClassLoader, other.childFirstClassLoader)
-      && Objects.equal(dependencies, other.dependencies);
+      && Objects.equal(dependencies, other.dependencies)
+      && Objects.equal(optionalDependencies, other.optionalDependencies);
   }
 
   /**
@@ -129,7 +132,7 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
   public int hashCode()
   {
     return Objects.hashCode(scmVersion, condition, information, resources,
-      childFirstClassLoader, dependencies);
+      childFirstClassLoader, dependencies, optionalDependencies);
   }
 
   /**
@@ -149,6 +152,7 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
                   .add("resources", resources)
                   .add("childFirstClassLoader", childFirstClassLoader)
                   .add("dependencies", dependencies)
+                  .add("optionalDependencies", optionalDependencies)
                   .toString();
     //J+
   }
@@ -186,6 +190,27 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
     return dependencies;
   }
 
+  /**
+   * Method description
+   *
+   *
+   * @return
+   *
+   * @since 2.0.0
+   */
+  public Set<String> getOptionalDependencies() {
+    if (optionalDependencies == null)
+    {
+      optionalDependencies = ImmutableSet.of();
+    }
+
+    return optionalDependencies;
+  }
+
+  public Set<String> getDependenciesInclusiveOptionals() {
+    return ImmutableSet.copyOf(Iterables.concat(getDependencies(), getOptionalDependencies()));
+  }
+
   /**
    * Method description
    *
@@ -246,6 +271,11 @@ public final class InstalledPluginDescriptor extends ScmModule implements Plugin
   @XmlElementWrapper(name = "dependencies")
   private Set<String> dependencies;
 
+  /** Field description */
+  @XmlElement(name = "dependency")
+  @XmlElementWrapper(name = "optional-dependencies")
+  private Set<String> optionalDependencies;
+
   /** Field description */
   @XmlElement(name = "information")
   private PluginInformation information;

scm-core/src/main/java/sonia/scm/plugin/ScmModule.java

@@ -89,9 +89,9 @@ public class ScmModule
    *
    * @return
    */
-  public Iterable<Class<?>> getExtensions()
+  public Iterable<ExtensionElement> getExtensions()
   {
-    return unwrap(extensions);
+    return nonNull(extensions);
   }
 
   /**
@@ -223,7 +223,7 @@ public class ScmModule
 
   /** Field description */
   @XmlElement(name = "extension")
-  private Set<ClassElement> extensions;
+  private Set<ExtensionElement> extensions;
 
   /** Field description */
   @XmlElement(name = "rest-provider")

scm-core/src/test/java/sonia/scm/plugin/ScmModuleTest.java

@@ -33,6 +33,7 @@ package sonia.scm.plugin;
 
 //~--- non-JDK imports --------------------------------------------------------
 
+import com.google.common.collect.Iterables;
 import com.google.common.io.Resources;
 
 import org.junit.Test;
@@ -69,10 +70,10 @@ public class ScmModuleTest
 
     //J-
     assertThat(
-      module.getExtensions(), 
+      Iterables.transform(module.getExtensions(), ExtensionElement::getClazz),
       containsInAnyOrder(
-        String.class,
-        Integer.class
+        String.class.getName(),
+        Integer.class.getName()
       )
     );
     assertThat(

scm-core/src/test/resources/sonia/scm/plugin/module.xml

@@ -47,10 +47,14 @@
 
   <extension>
     <class>java.lang.String</class>
+    <requires>scm-mail-plugin</requires>
+    <requires>scm-review-plugin</requires>
+    <description>ext01</description>
   </extension>
 
   <extension>
     <class>java.lang.Integer</class>
+    <description>ext02</description>
   </extension>
 
   <!-- rest providers -->

scm-ui/ui-components/src/__resources__/Diff.binary.ts

@@ -0,0 +1,18 @@
+export default `diff --git a/Main.java b/Main.java
+index 9b5ca13..7ced845 100644
+--- a/Main.java
++++ b/Main.java
+@@ -1,5 +1,5 @@
+  class Main {
+  -    public static void main(String[] args) {
+  +    public static void main(String[] arguments) {
+    System.out.println("Expect nothing more to happen.");
+  }
+}
+diff --git a/conflict.png b/conflict.png
+new file mode 100644
+index 0000000..7c77c7f
+--- /dev/null
++++ b/conflict.png
+Binary files differ
+`;

scm-ui/ui-components/src/__snapshots__/storyshots.test.ts.snap

@@ -334,6 +334,305 @@ exports[`Storyshots DateFromNow Default 1`] = `
 </div>
 `;
 
+exports[`Storyshots Diff Binaries 1`] = `
+Array [
+  <div
+    className="sc-iwsKbI czQDxz panel is-size-6"
+  >
+    <div
+      className="panel-heading"
+    >
+      <div
+        className="sc-gZMcBi hiXlnL level"
+      >
+        <div
+          className="sc-gqjmRU jMyrLy level-left is-flex has-cursor-pointer"
+          onClick={[Function]}
+          title="Main.java"
+        >
+          <i
+            className="fas fa-angle-down has-text-inherit"
+          />
+          <span
+            className="sc-VigVT kUVxiT is-ellipsis-overflow is-size-6"
+          >
+            Main.java
+          </span>
+          <span
+            className="tag is-info is-outlined sc-jzJRlG fdoJSr is-rounded has-text-weight-normal"
+          >
+            modify
+          </span>
+        </div>
+        <div
+          className="sc-jTzLTM ljPywG level-right is-flex"
+        >
+          <div
+            className="field is-grouped"
+          >
+            <div
+              className="control"
+            >
+              <button
+                className="button is-default is-reduced-mobile"
+                onClick={[Function]}
+                type="button"
+              >
+                <span
+                  className="icon is-medium"
+                >
+                  <i
+                    className="fas fa-columns has-text-inherit"
+                  />
+                </span>
+                <span>
+                  diff.sideBySide
+                   
+                </span>
+              </button>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+    <div
+      className="panel-block is-paddingless"
+    >
+      <table
+        className="diff diff-unified sc-cSHVUG cHkPoJ unified"
+        onMouseDown={[Function]}
+      >
+        <colgroup>
+          <col
+            className="diff-gutter-col"
+          />
+          <col
+            className="diff-gutter-col"
+          />
+          <col />
+        </colgroup>
+        <tbody
+          className="diff-decoration"
+        >
+          <tr>
+            <td
+              className="diff-decoration-content"
+              colSpan={3}
+            >
+              <span />
+            </td>
+          </tr>
+        </tbody>
+        <tbody
+          className="diff-hunk"
+        >
+          <tr
+            className="diff-line"
+          >
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              1
+            </td>
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              1
+            </td>
+            <td
+              className="diff-code diff-code-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+               class Main {
+            </td>
+          </tr>
+          <tr
+            className="diff-line"
+          >
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              2
+            </td>
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              2
+            </td>
+            <td
+              className="diff-code diff-code-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+               -    public static void main(String[] args) {
+            </td>
+          </tr>
+          <tr
+            className="diff-line"
+          >
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              3
+            </td>
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              3
+            </td>
+            <td
+              className="diff-code diff-code-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+               +    public static void main(String[] arguments) {
+            </td>
+          </tr>
+          <tr
+            className="diff-line"
+          >
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              4
+            </td>
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              4
+            </td>
+            <td
+              className="diff-code diff-code-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+                 System.out.println("Expect nothing more to happen.");
+            </td>
+          </tr>
+          <tr
+            className="diff-line"
+          >
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              5
+            </td>
+            <td
+              className="diff-gutter diff-gutter-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+              5
+            </td>
+            <td
+              className="diff-code diff-code-normal"
+              onMouseEnter={[Function]}
+              onMouseLeave={[Function]}
+            >
+               }
+            </td>
+          </tr>
+        </tbody>
+      </table>
+    </div>
+  </div>,
+  <div
+    className="sc-iwsKbI bGoZkF panel is-size-6"
+  >
+    <div
+      className="panel-heading"
+    >
+      <div
+        className="sc-gZMcBi hiXlnL level"
+      >
+        <div
+          className="sc-gqjmRU jMyrLy level-left is-flex has-cursor-pointer"
+          onClick={[Function]}
+          title="conflict.png"
+        >
+          <span
+            className="sc-VigVT kUVxiT is-ellipsis-overflow is-size-6"
+          >
+            conflict.png
+          </span>
+          <span
+            className="tag is-info is-outlined sc-jzJRlG fdoJSr is-rounded has-text-weight-normal"
+          >
+            add
+          </span>
+        </div>
+        <div
+          className="sc-jTzLTM ljPywG level-right is-flex"
+        >
+          <div
+            className="field is-grouped"
+          >
+            <div
+              className="control"
+            >
+              <button
+                className="button is-default is-reduced-mobile"
+                onClick={[Function]}
+                type="button"
+              >
+                <span
+                  className="icon is-medium"
+                >
+                  <i
+                    className="fas fa-columns has-text-inherit"
+                  />
+                </span>
+                <span>
+                  diff.sideBySide
+                   
+                </span>
+              </button>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+    <div
+      className="panel-block is-paddingless"
+    >
+      <table
+        className="diff diff-unified sc-cSHVUG cHkPoJ unified"
+        onMouseDown={[Function]}
+      >
+        <colgroup>
+          <col
+            className="diff-gutter-col"
+          />
+          <col
+            className="diff-gutter-col"
+          />
+          <col />
+        </colgroup>
+      </table>
+    </div>
+  </div>,
+]
+`;
+
 exports[`Storyshots Diff Collapsed 1`] = `
 Array [
   <div

scm-ui/ui-components/src/repos/Diff.stories.tsx

@@ -5,6 +5,7 @@ import Diff from "./Diff";
 import parser from "gitdiff-parser";
 import simpleDiff from "../__resources__/Diff.simple";
 import hunksDiff from "../__resources__/Diff.hunks";
+import binaryDiff from "../__resources__/Diff.binary";
 import Button from "../buttons/Button";
 import { DiffEventContext } from "./DiffTypes";
 import Toast from "../toast/Toast";
@@ -52,4 +53,8 @@ storiesOf("Diff", module)
   .add("Hunks", () => {
     const hunkDiffFiles = parser.parse(hunksDiff);
     return <Diff diff={hunkDiffFiles} />;
+  })
+  .add("Binaries", () => {
+    const binaryDiffFiles = parser.parse(binaryDiff);
+    return <Diff diff={binaryDiffFiles} />;
   });

scm-webapp/src/main/java/sonia/scm/plugin/DefaultPluginLoader.java

@@ -99,7 +99,7 @@ public class DefaultPluginLoader implements PluginLoader
 
       modules = getInstalled(parent, context, PATH_MODULECONFIG);
 
-      collector = new ExtensionCollector(Iterables.concat(modules, unwrap()));
+      collector = new ExtensionCollector(parent, modules, installedPlugins);
       extensionProcessor = new DefaultExtensionProcessor(collector);
     }
     catch (IOException | JAXBException ex)
@@ -170,19 +170,6 @@ public class DefaultPluginLoader implements PluginLoader
     return uberWebResourceLoader;
   }
 
-  //~--- methods --------------------------------------------------------------
-
-  /**
-   * Method description
-   *
-   *
-   * @return
-   */
-  private Iterable<InstalledPluginDescriptor> unwrap()
-  {
-    return PluginsInternal.unwrap(installedPlugins);
-  }
-
   //~--- get methods ----------------------------------------------------------
 
   /**

scm-webapp/src/main/java/sonia/scm/plugin/ExplodedSmp.java

@@ -98,8 +98,8 @@ public final class ExplodedSmp implements Comparable<ExplodedSmp>
   {
     int result;
 
-    Set<String> depends = plugin.getDependencies();
-    Set<String> odepends = o.plugin.getDependencies();
+    Set<String> depends = plugin.getDependenciesInclusiveOptionals();
+    Set<String> odepends = o.plugin.getDependenciesInclusiveOptionals();
 
     if (depends.isEmpty() && odepends.isEmpty())
     {

scm-webapp/src/main/java/sonia/scm/plugin/ExtensionBinder.java

@@ -55,63 +55,37 @@ import sonia.scm.util.Util;
 public final class ExtensionBinder
 {
 
-  /** Field description */
   private static final String TYPE_LOOSE_EXT = "loose extension";
-
-  /** Field description */
   private static final String TYPE_REST_RESOURCE = "rest resource";
+  private static final String AS_EAGER_SINGLETON = " as eager singleton";
 
   /**
    * the logger for ExtensionBinder
    */
-  private static final Logger logger =
-    LoggerFactory.getLogger(ExtensionBinder.class);
+  private static final Logger logger = LoggerFactory.getLogger(ExtensionBinder.class);
 
-  //~--- constructors ---------------------------------------------------------
-
-  /**
-   * Constructs ...
-   *
-   *
-   * @param binder
-   */
   public ExtensionBinder(Binder binder)
   {
     this.binder = binder;
   }
 
-  //~--- methods --------------------------------------------------------------
-
-  /**
-   * Method description
-   *
-   *
-   * @param collector
-   */
   public void bind(ExtensionCollector collector)
   {
-    logger.info("bind extensions to extension points");
+    logger.debug("bind extensions to extension points");
 
     for (ExtensionPointElement epe : collector.getExtensionPointElements())
     {
       bindExtensionPoint(collector, epe);
     }
 
-    logger.info("bind loose extensions");
+    logger.debug("bind loose extensions");
     bindLooseExtensions(collector.getLooseExtensions());
-    logger.info("bind rest providers");
+    logger.debug("bind rest providers");
     bindRestProviders(collector.getRestProviders());
-    logger.info("bind rest resources");
+    logger.debug("bind rest resources");
     bindRestResource(collector.getRestResources());
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param collector
-   * @param epe
-   */
   private void bindExtensionPoint(ExtensionCollector collector,
     ExtensionPointElement epe)
   {
@@ -142,12 +116,6 @@ public final class ExtensionBinder
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param extensions
-   */
   private void bindLooseExtensions(Iterable<Class> extensions)
   {
     for (Class extension : extensions)
@@ -156,46 +124,27 @@ public final class ExtensionBinder
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   *
-   * @param found
-   *
-   * @param extensionPoint
-   *
-   * @param boundClasses
-   * @param extensionPointClass
-   * @param extensions
-   */
-  private void bindMultiExtensionPoint(ExtensionPointElement extensionPoint,
-    Iterable<Class> extensions)
+  private void bindMultiExtensionPoint(ExtensionPointElement extensionPoint, Iterable<Class> extensions)
   {
     Class extensionPointClass = extensionPoint.getClazz();
 
-    if (logger.isInfoEnabled())
-    {
-      logger.info("create multibinder for {}", extensionPointClass.getName());
-    }
-
-    Multibinder multibinder = Multibinder.newSetBinder(binder,
-                                extensionPointClass);
+    logger.debug("create multibinder for {}", extensionPointClass.getName());
 
+    Multibinder multibinder = Multibinder.newSetBinder(binder, extensionPointClass);
     for (Class extensionClass : extensions)
     {
       boolean eagerSingleton = isEagerSingleton(extensionClass);
 
-      if (logger.isInfoEnabled())
+      if (logger.isDebugEnabled())
       {
         String as = Util.EMPTY_STRING;
 
         if (eagerSingleton)
         {
-          as = " as eager singleton";
+          as = AS_EAGER_SINGLETON;
         }
 
-        logger.info("bind {} to multibinder of {}{}", extensionClass.getName(),
+        logger.debug("bind {} to multibinder of {}{}", extensionClass.getName(),
           extensionPointClass.getName(), as);
       }
 
@@ -208,27 +157,15 @@ public final class ExtensionBinder
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param restProviders
-   */
   private void bindRestProviders(Iterable<Class> restProviders)
   {
     for (Class restProvider : restProviders)
     {
-      logger.info("bind rest provider {}", restProvider);
+      logger.debug("bind rest provider {}", restProvider);
       binder.bind(restProvider).in(Singleton.class);
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param restResources
-   */
   private void bindRestResource(Iterable<Class> restResources)
   {
     for (Class restResource : restResources)
@@ -237,31 +174,22 @@ public final class ExtensionBinder
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param extensionPointClass
-   *
-   * @param extensionPoint
-   * @param extensionClass
-   */
   private void bindSingleInstance(ExtensionPointElement extensionPoint,
     Class extensionClass)
   {
     Class extensionPointClass = extensionPoint.getClazz();
     boolean eagerSingleton = isEagerSingleton(extensionClass);
 
-    if (logger.isInfoEnabled())
+    if (logger.isDebugEnabled())
     {
       String as = Util.EMPTY_STRING;
 
       if (eagerSingleton)
       {
-        as = " as eager singleton";
+        as = AS_EAGER_SINGLETON;
       }
 
-      logger.info("bind {} to {}{}", extensionClass.getName(),
+      logger.debug("bind {} to {}{}", extensionClass.getName(),
         extensionPointClass.getName(), as);
     }
 
@@ -274,13 +202,6 @@ public final class ExtensionBinder
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param type
-   * @param extension
-   */
   private void singleBind(String type, Class extension)
   {
     StringBuilder log = new StringBuilder();
@@ -291,30 +212,19 @@ public final class ExtensionBinder
 
     if (isEagerSingleton(extension))
     {
-      log.append(" as eager singleton");
+      log.append(AS_EAGER_SINGLETON);
       abb.asEagerSingleton();
     }
 
-    logger.info(log.toString());
+    if (logger.isDebugEnabled()) {
+      logger.debug(log.toString());
+    }
   }
 
-  //~--- get methods ----------------------------------------------------------
-
-  /**
-   * Method description
-   *
-   *
-   * @param extensionClass
-   *
-   * @return
-   */
   private boolean isEagerSingleton(Class extensionClass)
   {
     return extensionClass.isAnnotationPresent(EagerSingleton.class);
   }
 
-  //~--- fields ---------------------------------------------------------------
-
-  /** Field description */
   private final Binder binder;
 }

scm-webapp/src/main/java/sonia/scm/plugin/ExtensionCollector.java

@@ -39,6 +39,8 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 //~--- JDK imports ------------------------------------------------------------
 
@@ -47,6 +49,7 @@ import java.util.Collections;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  *
@@ -56,23 +59,33 @@ import java.util.Set;
 public final class ExtensionCollector
 {
 
-  /**
-   * Constructs ...
-   *
-   *
-   * @param modules
-   */
-  ExtensionCollector(Iterable<ScmModule> modules)
-  {
-    for (ScmModule module : modules)
-    {
+  private static final Logger LOG = LoggerFactory.getLogger(ExtensionCollector.class);
+
+  private final Set<String> pluginIndex;
+
+  public ExtensionCollector(ClassLoader moduleClassLoader, Set<ScmModule> modules, Set<InstalledPlugin> installedPlugins) {
+    this.pluginIndex = createPluginIndex(installedPlugins);
+
+    for (ScmModule module : modules) {
       collectRootElements(module);
     }
-
-    for (ScmModule module : modules)
-    {
-      collectExtensions(module);
+    for (ScmModule plugin : PluginsInternal.unwrap(installedPlugins)) {
+      collectRootElements(plugin);
     }
+
+    for (ScmModule module : modules) {
+      collectExtensions(moduleClassLoader, module);
+    }
+
+    for (InstalledPlugin plugin : installedPlugins) {
+      collectExtensions(plugin.getClassLoader(), plugin.getDescriptor());
+    }
+  }
+
+  private Set<String> createPluginIndex(Set<InstalledPlugin> installedPlugins) {
+    return installedPlugins.stream()
+      .map(p -> p.getDescriptor().getInformation().getName())
+      .collect(Collectors.toSet());
   }
 
   //~--- methods --------------------------------------------------------------
@@ -245,19 +258,34 @@ public final class ExtensionCollector
     }
   }
 
-  /**
-   * Method description
-   *
-   *
-   * @param module
-   */
-  private void collectExtensions(ScmModule module)
-  {
-    for (Class extension : module.getExtensions())
-    {
-      appendExtension(extension);
+  private void collectExtensions(ClassLoader defaultClassLoader, ScmModule module) {
+    for (ExtensionElement extension : module.getExtensions()) {
+      if (isRequirementFulfilled(extension)) {
+        Class<?> extensionClass = loadExtension(defaultClassLoader, extension);
+        appendExtension(extensionClass);
       }
     }
+  }
+
+  private Class<?> loadExtension(ClassLoader classLoader, ExtensionElement extension) {
+    try {
+      return classLoader.loadClass(extension.getClazz());
+    } catch (ClassNotFoundException ex) {
+      throw new PluginLoadException("failed to load clazz", ex);
+    }
+  }
+
+  private boolean isRequirementFulfilled(ExtensionElement extension) {
+    if (extension.getRequires() != null) {
+      for (String requiredPlugin : extension.getRequires()) {
+        if (!pluginIndex.contains(requiredPlugin)) {
+          LOG.debug("skip loading of extension {}, because the required plugin {} is not installed", extension.getClazz(), requiredPlugin);
+          return false;
+        }
+      }
+    }
+    return true;
+  }
 
   /**
    * Method description

scm-webapp/src/main/java/sonia/scm/plugin/PluginProcessor.java

@@ -189,7 +189,7 @@ public final class PluginProcessor
 
     PluginTree pluginTree = new PluginTree(smps);
 
-    logger.trace("build plugin tree: {}", pluginTree);
+    logger.info("install plugin tree:\n{}", pluginTree);
 
     List<PluginNode> rootNodes = pluginTree.getRootNodes();
 

scm-webapp/src/main/java/sonia/scm/plugin/PluginTree.java

@@ -35,15 +35,13 @@ package sonia.scm.plugin;
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Ordering;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-//~--- JDK imports ------------------------------------------------------------
-
 import java.util.Arrays;
 import java.util.List;
-import java.util.Set;
+
+//~--- JDK imports ------------------------------------------------------------
 
 /**
  *
@@ -104,9 +102,7 @@ public final class PluginTree
 
       if ((condition == null) || condition.isSupported())
       {
-        Set<String> dependencies = plugin.getDependencies();
-
-        if ((dependencies == null) || dependencies.isEmpty())
+        if (plugin.getDependencies().isEmpty() && plugin.getOptionalDependencies().isEmpty())
         {
           rootNodes.add(new PluginNode(smp));
         }
@@ -170,6 +166,20 @@ public final class PluginTree
         //J+
       }
     }
+
+    boolean rootNode = smp.getPlugin().getDependencies().isEmpty();
+    for (String dependency : smp.getPlugin().getOptionalDependencies()) {
+      if (appendNode(rootNodes, child, dependency)) {
+        rootNode = false;
+      } else {
+        logger.info("optional dependency {} of {} is not installed", dependency, child.getId());
+      }
+    }
+
+    if (rootNode) {
+      logger.info("could not find optional dependencies of {}, append it as root node", child.getId());
+      rootNodes.add(new PluginNode(smp));
+    }
   }
 
   /**
@@ -212,7 +222,18 @@ public final class PluginTree
 
   @Override
   public String toString() {
-    return "plugin tree: " + rootNodes.toString();
+    StringBuilder buffer = new StringBuilder();
+    for (PluginNode node : rootNodes) {
+      append(buffer, "", node);
+    }
+    return buffer.toString();
+  }
+
+  private void append(StringBuilder buffer, String indent, PluginNode node) {
+    buffer.append(indent).append("+- ").append(node.getId()).append("\n");
+    for (PluginNode child : node.getChildren()) {
+      append(buffer, indent + "   ", child);
+    }
   }
 //~--- fields ---------------------------------------------------------------
 

scm-webapp/src/test/java/sonia/scm/plugin/ExplodedSmpTest.java

@@ -134,7 +134,7 @@ public class ExplodedSmpTest
     info.setVersion(version);
 
     InstalledPluginDescriptor plugin = new InstalledPluginDescriptor(2, info, null, null, false,
-                      Sets.newSet(dependencies));
+                      Sets.newSet(dependencies), null);
 
     return new ExplodedSmp(null, plugin);
   }

scm-webapp/src/test/java/sonia/scm/plugin/PluginTreeTest.java

@@ -34,6 +34,7 @@ package sonia.scm.plugin;
 //~--- non-JDK imports --------------------------------------------------------
 
 import com.google.common.base.Function;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 
 import org.junit.Rule;
@@ -72,7 +73,7 @@ public class PluginTreeTest
     PluginCondition condition = new PluginCondition("999",
                                   new ArrayList<String>(), "hit");
     InstalledPluginDescriptor plugin = new InstalledPluginDescriptor(2, createInfo("a",  "1"), null, condition,
-                      false, null);
+                      false, null, null);
     ExplodedSmp smp = createSmp(plugin);
 
     new PluginTree(smp).getRootNodes();
@@ -115,7 +116,7 @@ public class PluginTreeTest
   public void testScmVersion() throws IOException
   {
     InstalledPluginDescriptor plugin = new InstalledPluginDescriptor(1, createInfo("a", "1"), null, null, false,
-                      null);
+                      null, null);
     ExplodedSmp smp = createSmp(plugin);
 
     new PluginTree(smp).getRootNodes();
@@ -152,6 +153,61 @@ public class PluginTreeTest
     assertThat(unwrapIds(b.getChildren()), containsInAnyOrder("c"));
   }
 
+  @Test
+  public void testWithOptionalDependency() throws IOException {
+    ExplodedSmp[] smps = new ExplodedSmp[] {
+      createSmpWithDependency("a"),
+      createSmpWithDependency("b", null, ImmutableSet.of("a")),
+      createSmpWithDependency("c", null, ImmutableSet.of("a", "b"))
+    };
+
+    PluginTree tree = new PluginTree(smps);
+    List<PluginNode> rootNodes = tree.getRootNodes();
+
+    assertThat(unwrapIds(rootNodes), containsInAnyOrder("a"));
+
+    PluginNode a = rootNodes.get(0);
+    assertThat(unwrapIds(a.getChildren()), containsInAnyOrder("b", "c"));
+
+    PluginNode b = a.getChild("b");
+    assertThat(unwrapIds(b.getChildren()), containsInAnyOrder("c"));
+  }
+
+  @Test
+  public void testWithDeepOptionalDependency() throws IOException {
+    ExplodedSmp[] smps = new ExplodedSmp[] {
+      createSmpWithDependency("a"),
+      createSmpWithDependency("b", "a"),
+      createSmpWithDependency("c", null, ImmutableSet.of("b"))
+    };
+
+    PluginTree tree = new PluginTree(smps);
+
+    System.out.println(tree);
+
+    List<PluginNode> rootNodes = tree.getRootNodes();
+
+    assertThat(unwrapIds(rootNodes), containsInAnyOrder("a"));
+
+    PluginNode a = rootNodes.get(0);
+    assertThat(unwrapIds(a.getChildren()), containsInAnyOrder("b"));
+
+    PluginNode b = a.getChild("b");
+    assertThat(unwrapIds(b.getChildren()), containsInAnyOrder("c"));
+  }
+
+  @Test
+  public void testWithNonExistentOptionalDependency() throws IOException {
+    ExplodedSmp[] smps = new ExplodedSmp[] {
+      createSmpWithDependency("a", null, ImmutableSet.of("b"))
+    };
+
+    PluginTree tree = new PluginTree(smps);
+    List<PluginNode> rootNodes = tree.getRootNodes();
+
+    assertThat(unwrapIds(rootNodes), containsInAnyOrder("a"));
+  }
+
   /**
    * Method description
    *
@@ -200,7 +256,7 @@ public class PluginTreeTest
   private ExplodedSmp createSmp(String name) throws IOException
   {
     return createSmp(new InstalledPluginDescriptor(2, createInfo(name, "1.0.0"), null, null,
-      false, null));
+      false, null, null));
   }
 
   /**
@@ -224,10 +280,19 @@ public class PluginTreeTest
     {
       dependencySet.add(d);
     }
+    return createSmpWithDependency(name, dependencySet, null);
+  }
 
-    InstalledPluginDescriptor plugin = new InstalledPluginDescriptor(2, createInfo(name, "1"), null, null,
-                      false, dependencySet);
-
+  private ExplodedSmp createSmpWithDependency(String name, Set<String> dependencies, Set<String> optionalDependencies) throws IOException {
+    InstalledPluginDescriptor plugin = new InstalledPluginDescriptor(
+      2,
+      createInfo(name, "1"),
+      null,
+      null,
+      false,
+      dependencies,
+      optionalDependencies
+    );
     return createSmp(plugin);
   }
 

yarn.lock

@@ -7332,9 +7332,9 @@ gitconfiglocal@^1.0.0:
   dependencies:
     ini "^1.3.2"
 
-gitdiff-parser@^0.1.2, "gitdiff-parser@https://github.com/scm-manager/gitdiff-parser#6baa7278824ecd17a199d842ca720d0453f68982":
+gitdiff-parser@^0.1.2, "gitdiff-parser@https://github.com/scm-manager/gitdiff-parser#ed3fe7de73dbb0a06c3e6adbbdf22dbae6e66351":
   version "0.1.2"
-  resolved "https://github.com/scm-manager/gitdiff-parser#6baa7278824ecd17a199d842ca720d0453f68982"
+  resolved "https://github.com/scm-manager/gitdiff-parser#ed3fe7de73dbb0a06c3e6adbbdf22dbae6e66351"
 
 glob-parent@^3.1.0:
   version "3.1.0"