documenting what this method does

core/src/main/java/hudson/model/ParameterValue.java

@@ -259,6 +259,15 @@ public abstract class ParameterValue implements Serializable {
     }
 
     /**
+     * Controls where the build (that this parameter is submitted to) will happen.
+     *
+     * @return
+     *      null to run the build where it normally runs. If non-null, this will
+     *      override {@link AbstractProject#getAssignedLabel()}. If a build is
+     *      submitted with multiple parameters, the first one that returns non-null
+     *      from this method will win, and all others won't be consulted.
+     *
+     *
      * @since 1.414
      */
     public Label getAssignedLabel(SubTask task) {