Document AbstractDaemonTest.commonServer

Change-Id: I958faccd81ae1f6ef13adbc968844279a3f6e7c6

java/com/google/gerrit/acceptance/AbstractDaemonTest.java

diff --git a/java/com/google/gerrit/acceptance/AbstractDaemonTest.java b/java/com/google/gerrit/acceptance/AbstractDaemonTest.java
index a933dac..ca105f6 100644
--- a/java/com/google/gerrit/acceptance/AbstractDaemonTest.java
+++ b/java/com/google/gerrit/acceptance/AbstractDaemonTest.java
@@ -193,7 +193,13 @@
 
 @RunWith(ConfigSuite.class)
 public abstract class AbstractDaemonTest {
+
+  /**
+   * Test methods without special annotations will use a common server for efficiency reasons. The
+   * server is torn down after the test class is done.
+   */
   private static GerritServer commonServer;
+
   private static Description firstTest;
 
   @ClassRule public static TemporaryFolder temporaryFolder = new TemporaryFolder();