Refactor LabelId out of PatchSetApprovals

Decouple the LabelId from the PatchSetApprovals so that we can
apply a vote in another context.  Specifically, we may want to
apply a vote(s) to a PatchSetVerification, a separate approval
channel for test results that may verify a single patchset.

Change-Id: Ibb162a6a9249204c24c8751ea01fb816586449dd

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/LabelId.java

@@ -0,0 +1,57 @@
+// Copyright (C) 2015 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.reviewdb.client;
+
+import com.google.gwtorm.client.Column;
+import com.google.gwtorm.client.StringKey;
+
+public class LabelId extends StringKey<com.google.gwtorm.client.Key<?>> {
+  private static final long serialVersionUID = 1L;
+
+  public static final LabelId SUBMIT = new LabelId("SUBM");
+
+  @Column(id = 1)
+  protected String id;
+
+  protected LabelId() {
+  }
+
+  public LabelId(final String n) {
+    id = n;
+  }
+
+  @Override
+  public String get() {
+    return id;
+  }
+
+  @Override
+  protected void set(String newValue) {
+    id = newValue;
+  }
+
+  @Override
+  public int hashCode() {
+    return get().hashCode();
+  }
+
+  @Override
+  public boolean equals(Object b) {
+    if (this == b) {
+      return get().equals(((LabelId) b).get());
+    }
+    return false;
+  }
+}

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/PatchSetApproval.java

@@ -16,53 +16,12 @@ package com.google.gerrit.reviewdb.client;
 
 import com.google.gwtorm.client.Column;
 import com.google.gwtorm.client.CompoundKey;
-import com.google.gwtorm.client.StringKey;
 
 import java.sql.Timestamp;
 import java.util.Objects;
 
 /** An approval (or negative approval) on a patch set. */
 public final class PatchSetApproval {
-  public static class LabelId extends
-      StringKey<com.google.gwtorm.client.Key<?>> {
-    private static final long serialVersionUID = 1L;
-
-    public static final LabelId SUBMIT = new LabelId("SUBM");
-
-    @Column(id = 1)
-    protected String id;
-
-    protected LabelId() {
-    }
-
-    public LabelId(final String n) {
-      id = n;
-    }
-
-    @Override
-    public String get() {
-      return id;
-    }
-
-    @Override
-    protected void set(String newValue) {
-      id = newValue;
-    }
-
-    @Override
-    public int hashCode() {
-      return get().hashCode();
-    }
-
-    @Override
-    public boolean equals(Object b) {
-      if (b instanceof LabelId) {
-        return get().equals(((LabelId) b).get());
-      }
-      return false;
-    }
-  }
-
   public static class Key extends CompoundKey<PatchSet.Id> {
     private static final long serialVersionUID = 1L;