Document classes in com.google.gerrit.index.project

This follows the style of the javadoc that has been added by change
Ia28579526 for the other indexes.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Ib4fd8fdaf944e734a7d97403ad8585b704a64e39

java/com/google/gerrit/index/project/IndexedProjectQuery.java

@@ -22,6 +22,10 @@ import com.google.gerrit.index.query.IndexedQuery;
 import com.google.gerrit.index.query.Predicate;
 import com.google.gerrit.index.query.QueryParseException;
 
+/**
+ * Wrapper around {@link Predicate}s that are returned by the {@link
+ * com.google.gerrit.index.IndexRewriter}. See {@link IndexedQuery}.
+ */
 public class IndexedProjectQuery extends IndexedQuery<Project.NameKey, ProjectData>
     implements DataSource<ProjectData> {
 

java/com/google/gerrit/index/project/ProjectData.java

@@ -23,6 +23,11 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
+/**
+ * Representation of a Gerrit project in the project index.
+ *
+ * <p>Includes information about all parent projects.
+ */
 public class ProjectData {
   private final Project project;
   private final Optional<ProjectData> parent;

java/com/google/gerrit/index/project/ProjectIndex.java

@@ -19,6 +19,10 @@ import com.google.gerrit.index.Index;
 import com.google.gerrit.index.IndexDefinition;
 import com.google.gerrit.index.query.Predicate;
 
+/**
+ * Index for Gerrit projects (repositories). This class is mainly used for typing the generic parent
+ * class that contains actual implementations.
+ */
 public interface ProjectIndex extends Index<Project.NameKey, ProjectData> {
 
   public interface Factory

java/com/google/gerrit/index/project/ProjectIndexCollection.java

@@ -19,6 +19,7 @@ import com.google.gerrit.entities.Project;
 import com.google.gerrit.index.IndexCollection;
 import com.google.inject.Singleton;
 
+/** Collection of active project indices. See {@link IndexCollection} for details on collections. */
 @Singleton
 public class ProjectIndexCollection
     extends IndexCollection<Project.NameKey, ProjectData, ProjectIndex> {

java/com/google/gerrit/index/project/ProjectIndexRewriter.java

@@ -23,6 +23,7 @@ import com.google.gerrit.index.query.QueryParseException;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 
+/** Rewriter for the project index. See {@link IndexRewriter} for details. */
 @Singleton
 public class ProjectIndexRewriter implements IndexRewriter<ProjectData> {
   private final ProjectIndexCollection indexes;

java/com/google/gerrit/index/project/ProjectIndexer.java

@@ -16,6 +16,7 @@ package com.google.gerrit.index.project;
 
 import com.google.gerrit.entities.Project;
 
+/** Interface for indexing a Gerrit project. */
 public interface ProjectIndexer {
 
   /**