Add documentation for glob and regex syntaxes

plugin/src/main/resources/io/jenkins/plugins/coverage/metrics/steps/CoverageRecorder/help-sourceDirectories.html

@@ -1,8 +1,35 @@
 <div>
-    Select additional folders that contain the source code files of the job.
-    Since the plugin also reads the affected source code files it needs to copy these files from the agent to the
-    controller. If these files are not part of the workspace (or checked out into a sub folder of the workspace) they
-    are not automatically found. So you can add one or more source code directories where the plugin tries to find
-    these files. Note, that due to security restrictions additional paths outside the workspace need to be registered
-    in Jenkins system configuration before they can be used here.
+    <p>
+        Select additional folders that contain the source code files of the job.
+        Since the plugin also reads the affected source code files it needs to copy these files from the agent to the
+        controller. If these files are not part of the workspace (or checked out into a sub folder of the workspace) they
+        are not automatically found. So you can add one or more source code directories where the plugin tries to find
+        these files. You can add relative paths in the workspace root, absolute paths, or expressions using the glob or
+        regexp syntaxes that are supported by the Java
+        <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/nio/file/FileSystem.html#getPathMatcher(java.lang.String)" target="_blank"
+           rel="noopener noreferrer">FileSystem#getPathMatcher</a> implementation.
+        Note, that due to security restrictions additional paths outside the workspace need to be registered
+        in Jenkins system configuration before they can be used here.
+    </p>
+
+    Examples for the syntax and pattern property:
+    <dl>
+        <dt>submodule/src/main/java</dt>
+        <dd>
+            Relative path <code>submodule/src/main/java</code> in the Jenkins workspace.
+        </dd>
+        <dt>glob:**/src/main/java</dt>
+        <dd>
+            A glob that expands to all folders in the Jenkins workspace that contain the sub-path <code>src/main/java</code>.
+        </dd>
+        <dt>regex:sources.*/src/main/java</dt>
+        <dd>
+            A regular expression that matches all folders in the Jenkins workspace that start with <code>sources</code> and end with the text <code>src/main/java</code>.
+        </dd>
+        <dt>C:\work\sources</dt>
+        <dd>
+            Absolute path on the <b>agent</b> that builds the sources. This folder must also be approved by a Jenkins
+            administrator in Jenkins global configuration.
+        </dd>
+    </dl>
 </div>

plugin/src/main/resources/io/jenkins/plugins/coverage/metrics/steps/CoverageStep/help-sourceDirectories.html

@@ -1,8 +1,39 @@
 <div>
-    Select additional folders that contain the source code files of the job.
-    Since the plugin also reads the affected source code files it needs to copy these files from the agent to the
-    controller. If these files are not part of the workspace (or checked out into a sub folder of the workspace) they
-    are not automatically found. So you can add one or more source code directories where the plugin tries to find
-    these files. Note, that due to security restrictions additional paths outside the workspace need to be registered
-    in Jenkins system configuration before they can be used here.
+    <p>
+        Select additional folders that contain the source code files of the job.
+        Since the plugin also reads the affected source code files it needs to copy these files from the agent to the
+        controller. If these files are not part of the workspace (or checked out into a sub folder of the workspace)
+        they
+        are not automatically found. So you can add one or more source code directories where the plugin tries to find
+        these files. You can add relative paths in the workspace root, absolute paths, or expressions using the glob or
+        regexp syntaxes that are supported by the Java
+        <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/nio/file/FileSystem.html#getPathMatcher(java.lang.String)"
+           target="_blank"
+           rel="noopener noreferrer">FileSystem#getPathMatcher</a> implementation.
+        Note, that due to security restrictions additional paths outside the workspace need to be registered
+        in Jenkins system configuration before they can be used here.
+    </p>
+
+    Examples for the syntax and pattern property:
+    <dl>
+        <dt>submodule/src/main/java</dt>
+        <dd>
+            Relative path <code>submodule/src/main/java</code> in the Jenkins workspace.
+        </dd>
+        <dt>glob:**/src/main/java</dt>
+        <dd>
+            A glob that expands to all folders in the Jenkins workspace that contain the sub-path
+            <code>src/main/java</code>.
+        </dd>
+        <dt>regex:sources.*/src/main/java</dt>
+        <dd>
+            A regular expression that matches all folders in the Jenkins workspace that start with <code>sources</code>
+            and end with the text <code>src/main/java</code>.
+        </dd>
+        <dt>C:\work\sources</dt>
+        <dd>
+            Absolute path on the <b>agent</b> that builds the sources. This folder must also be approved by a Jenkins
+            administrator in Jenkins global configuration.
+        </dd>
+    </dl>
 </div>