Address review comments

src/main/java/org/codehaus/mojo/license/AbstractAddThirdPartyMojo.java

@@ -562,10 +562,32 @@ public abstract class AbstractAddThirdPartyMojo
      */
     private Map<String, String> globalKnownLicenses;
 
-    boolean isAggregatorBuild;
+    /**
+     * Whether this is an aggregate build, or a single-project goal. This setting determines which dependency artifacts
+     * will be examined by the plugin. AddThirdParty needs to load dependencies only for the single project it is run
+     * for, while AggregateAddThirdParty needs to load dependencies for the parent project, as well as all child
+     * projects in the reactor.
+     */
+    boolean isAggregatorBuild = false;
 
+    /**
+     * Map from reactor project G/A to direct dependencies. When loading dependencies, the aggregator goal replaces all
+     * reactor projects with their direct dependencies, to avoid trying to load artifacts for projects that haven't been
+     * built/published yet. This field is used to keep track of which dependencies are also projects in the reactor.
+     */
     Map<String, List<Dependency>> reactorProjectDependencies;
 
+    /**
+     * Copies of the project's dependency sets. AddThirdParty needs to load dependencies only for the single project it
+     * is run for, while AggregateAddThirdParty needs to load dependencies for the parent project, as well as all child
+     * projects in the reactor.
+     *
+     * The aggregator goal replaces all reactor projects with their direct dependencies, to avoid trying to load
+     * artifacts for projects that haven't been built/published yet. This is necessary in cases where one child project
+     * A in a reactor depends on another project B in the same reactor. Since B is not necessarily built/published, the
+     * plugin needs to replace B with its dependencies when processing A. This field stores that modified view of the
+     * project's dependencies.
+     */
     LoadedProjectDependencies dependencyArtifacts;
 
     // ----------------------------------------------------------------------
@@ -643,10 +665,10 @@ protected void init()
             doGenerateBundle = false;
         }
 
-        if (isAggregatorBuild) {
+        if ( isAggregatorBuild ) {
             dependencyArtifacts = dependenciesTool.loadProjectArtifacts( localRepository, remoteRepositories, project, reactorProjectDependencies );
         } else {
-            dependencyArtifacts = new LoadedProjectDependencies(project.getArtifacts(), project.getDependencyArtifacts());
+            dependencyArtifacts = new LoadedProjectDependencies( project.getArtifacts(), project.getDependencyArtifacts() );
         }
 
         projectDependencies = loadDependencies();

src/main/java/org/codehaus/mojo/license/AbstractDownloadLicensesMojo.java

@@ -265,7 +265,7 @@ protected MavenProject getProject()
     protected SortedMap<String, MavenProject> getDependencies( MavenProject project )
     {
         return dependenciesTool.loadProjectDependencies( 
-                new LoadedProjectDependencies(project.getArtifacts(), project.getDependencyArtifacts()),
+                new LoadedProjectDependencies( project.getArtifacts(), project.getDependencyArtifacts() ),
                 this, localRepository, remoteRepositories, null );
     }
 

src/main/java/org/codehaus/mojo/license/AggregatorAddThirdPartyMojo.java

@@ -160,7 +160,7 @@ protected void init() throws Exception {
         isAggregatorBuild = true;
         reactorProjectDependencies = new TreeMap<>();
         for (MavenProject reactorProject : this.reactorProjects) {
-            reactorProjectDependencies.put(String.format("%s:%s", reactorProject.getGroupId(), reactorProject.getArtifactId()), reactorProject.getDependencies());
+            reactorProjectDependencies.put( String.format( "%s:%s", reactorProject.getGroupId(), reactorProject.getArtifactId() ), reactorProject.getDependencies() );
         }
         super.init();
     }

src/main/java/org/codehaus/mojo/license/api/DefaultDependenciesTool.java

@@ -26,7 +26,6 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -137,12 +136,12 @@ public SortedMap<String, MavenProject> loadProjectDependencies( LoadedProjectDep
         if ( configuration.isIncludeTransitiveDependencies() )
         {
             // All project dependencies
-            depArtifacts = Collections.unmodifiableSet(artifacts.getAllDependencies());
+            depArtifacts = artifacts.getAllDependencies();
         }
         else
         {
             // Only direct project dependencies
-            depArtifacts = Collections.unmodifiableSet(artifacts.getDirectDependencies());
+            depArtifacts = artifacts.getDirectDependencies();
         }
 
         List<String> includedScopes = configuration.getIncludedScopes();

src/main/java/org/codehaus/mojo/license/api/LoadedProjectDependencies.java

@@ -1,28 +1,63 @@
 
 package org.codehaus.mojo.license.api;
 
+import edu.emory.mathcs.backport.java.util.Collections;
+import java.util.HashSet;
 import java.util.Set;
 import org.apache.maven.artifact.Artifact;
 
+/*
+ * #%L
+ * License Maven Plugin
+ * %%
+ * Copyright (C) 2008 - 2012 CodeLutin, Codehaus, Tony Chemit
+ * %%
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Lesser Public License for more details.
+ *
+ * You should have received a copy of the GNU General Lesser Public
+ * License along with this program.  If not, see
+ * <http://www.gnu.org/licenses/lgpl-3.0.html>.
+ * #L%
+ */
+
+/**
+ * Copies of the project's dependency sets. AddThirdParty needs to load dependencies only for the single project it is
+ * run for, while AggregateAddThirdParty needs to load dependencies for the parent project, as well as all child
+ * projects in the reactor.
+ *
+ * The aggregator goal replaces all reactor projects with their direct dependencies, to avoid trying to load artifacts
+ * for projects that haven't been built/published yet. This is necessary in cases where one child project A in a reactor
+ * depends on another project B in the same reactor. Since B is not necessarily built/published, the plugin needs to
+ * replace B with its dependencies when processing A. This field stores that modified view of the project's
+ * dependencies.
+ */
 public class LoadedProjectDependencies {
 
     private final Set<Artifact> allDependencies;
     private final Set<Artifact> directDependencies;
 
     public LoadedProjectDependencies( Set<Artifact> allDependencies, Set<Artifact> directDependencies )
     {
-        this.allDependencies = allDependencies;
-        this.directDependencies = directDependencies;
+        this.allDependencies = new HashSet<>( allDependencies );
+        this.directDependencies = new HashSet<>( directDependencies );
     }
 
     public Set<Artifact> getAllDependencies()
     {
-        return allDependencies;
+        return Collections.unmodifiableSet( allDependencies );
     }
 
     public Set<Artifact> getDirectDependencies()
     {
-        return directDependencies;
+        return Collections.unmodifiableSet( directDependencies );
     }
 
 }