HBASE-25240 gson format of RpcServer.logResponse is abnormal

Closes #2623

Signed-off-by: Viraj Jasani <vjasani@apache.org>

hbase-common/src/main/java/org/apache/hadoop/hbase/util/GsonUtil.java

@@ -58,4 +58,8 @@ public final class GsonUtil {
         }
       });
   }
+
+  public static GsonBuilder createGsonWithDisableHtmlEscaping() {
+    return createGson().disableHtmlEscaping();
+  }
 }

hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestGsonUtil.java

@@ -0,0 +1,48 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.hadoop.hbase.util;
+
+import static org.junit.Assert.assertEquals;
+
+import org.apache.hadoop.hbase.HBaseClassTestRule;
+import org.apache.hadoop.hbase.testclassification.MiscTests;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.apache.hbase.thirdparty.com.google.gson.Gson;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+@Category({ MiscTests.class, SmallTests.class })
+public class TestGsonUtil {
+
+  @ClassRule
+  public static final HBaseClassTestRule CLASS_RULE =
+    HBaseClassTestRule.forClass(TestGsonUtil.class);
+
+  private static final Gson GSON = GsonUtil.createGson().create();
+  private static final Gson DHE_GSON = GsonUtil.createGsonWithDisableHtmlEscaping().create();
+
+  @Test
+  public void testDisableHtmlEscaping() {
+    // enable html escaping, turn '=' into '\u003d'
+    assertEquals("\"\\u003d\\u003d\\u003d\"", GSON.toJson("==="));
+
+    // disable html escaping
+    assertEquals("\"===\"", DHE_GSON.toJson("==="));
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServer.java

@@ -200,7 +200,7 @@ public abstract class RpcServer implements RpcServerInterface,
   protected static final String TRACE_LOG_MAX_LENGTH = "hbase.ipc.trace.log.max.length";
   protected static final String KEY_WORD_TRUNCATED = " <TRUNCATED>";
 
-  protected static final Gson GSON = GsonUtil.createGson().create();
+  protected static final Gson GSON = GsonUtil.createGsonWithDisableHtmlEscaping().create();
 
   protected final int maxRequestSize;
   protected final int warnResponseTime;