Account API: Add method to get account by integer ID

Change-Id: I7a1e7b15149892465564eaeab38c7a111386696e

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/accounts/AccountIT.java

@@ -140,6 +140,19 @@ public class AccountIT extends AbstractDaemonTest {
     assertThat(info.username).isEqualTo("admin");
   }
 
+  @Test
+  public void getByIntId() throws Exception {
+    AccountInfo info = gApi
+        .accounts()
+        .id("admin")
+        .get();
+    AccountInfo infoByIntId = gApi
+        .accounts()
+        .id(info._accountId)
+        .get();
+    assertThat(info.name).isEqualTo(infoByIntId.name);
+  }
+
   @Test
   public void self() throws Exception {
     AccountInfo info = gApi

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/accounts/Accounts.java

@@ -37,6 +37,11 @@ public interface Accounts {
    */
   AccountApi id(String id) throws RestApiException;
 
+  /**
+   * @see #id(String)
+   */
+  AccountApi id(int id) throws RestApiException;
+
   /**
    * Look up the account of the current in-scope user.
    *
@@ -117,6 +122,11 @@ public interface Accounts {
       throw new NotImplementedException();
     }
 
+    @Override
+    public AccountApi id(int id) throws RestApiException {
+      throw new NotImplementedException();
+    }
+
     @Override
     public AccountApi self() throws RestApiException {
       throw new NotImplementedException();

gerrit-server/src/main/java/com/google/gerrit/server/api/accounts/AccountsImpl.java

@@ -60,6 +60,11 @@ public class AccountsImpl implements Accounts {
     }
   }
 
+  @Override
+  public AccountApi id(int id) throws RestApiException {
+    return id(String.valueOf(id));
+  }
+
   @Override
   public AccountApi self() throws RestApiException {
     if (!self.get().isIdentifiedUser()) {