Restructure the public API for server

pkg/analysis_server/lib/plugin/analysis/occurrences/occurrences_core.dart

Index: pkg/analysis_server/lib/plugin/analysis/occurrences/occurrences_core.dart
diff --git a/pkg/analysis_server/lib/analysis/occurrences_core.dart b/pkg/analysis_server/lib/plugin/analysis/occurrences/occurrences_core.dart
similarity index 94%
rename from pkg/analysis_server/lib/analysis/occurrences_core.dart
rename to pkg/analysis_server/lib/plugin/analysis/occurrences/occurrences_core.dart
index 2e24a9b3c798093dc63cfd4e520c89f8ee211572..6975520de3ac832c61d3b1974b83b56716fec388 100644
--- a/pkg/analysis_server/lib/analysis/occurrences_core.dart
+++ b/pkg/analysis_server/lib/plugin/analysis/occurrences/occurrences_core.dart
@@ -2,34 +2,34 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library analysis_server.analysis.occurrences_core;
+library analysis_server.plugin.analysis.occurrences.occurrences_core;
 
 import 'package:analysis_server/src/protocol.dart' show Element, Occurrences;
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
 import 'package:analyzer/src/generated/source.dart' show Source;
 
 /**
- * An object used to produce occurrences.
+ * An object that [OccurrencesContributor]s use to record occurrences into.
  *
- * Clients are expected to subtype this class when implementing plugins.
+ * Clients are not expected to subtype this class.
  */
-abstract class OccurrencesContributor {
+abstract class OccurrencesCollector {
   /**
-   * Contribute occurrences into the given [collector].
-   * The [context] can be used to get analysis results.
+   * Record a new element occurrences.
    */
-  void computeOccurrences(
-      OccurrencesCollector collector, AnalysisContext context, Source source);
+  void addOccurrences(Occurrences occurrences);
 }
 
 /**
- * An object that [OccurrencesContributor]s use to record occurrences into.
+ * An object used to produce occurrences.
  *
- * Clients are not expected to subtype this class.
+ * Clients are expected to subtype this class when implementing plugins.
  */
-abstract class OccurrencesCollector {
+abstract class OccurrencesContributor {
   /**
-   * Record a new element occurrences.
+   * Contribute occurrences into the given [collector].
+   * The [context] can be used to get analysis results.
    */
-  void addOccurrences(Occurrences occurrences);
+  void computeOccurrences(
+      OccurrencesCollector collector, AnalysisContext context, Source source);
 }