resultFormat name in camel case (#11585)

* resultFormat name in camel case

* test for letter case

sql/src/main/java/org/apache/druid/sql/http/ResultFormat.java

@@ -20,6 +20,7 @@
 package org.apache.druid.sql.http;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.apache.druid.java.util.common.StringUtils;
 
@@ -32,7 +33,7 @@ import java.util.List;
 
 public enum ResultFormat
 {
-  ARRAY {
+  ARRAY("array") {
     @Override
     public String contentType()
     {
@@ -46,7 +47,7 @@ public enum ResultFormat
     }
   },
 
-  ARRAYLINES {
+  ARRAYLINES("arrayLines") {
     @Override
     public String contentType()
     {
@@ -60,7 +61,7 @@ public enum ResultFormat
     }
   },
 
-  CSV {
+  CSV("csv") {
     @Override
     public String contentType()
     {
@@ -74,7 +75,7 @@ public enum ResultFormat
     }
   },
 
-  OBJECT {
+  OBJECT("object") {
     @Override
     public String contentType()
     {
@@ -88,7 +89,7 @@ public enum ResultFormat
     }
   },
 
-  OBJECTLINES {
+  OBJECTLINES("objectLines") {
     @Override
     public String contentType()
     {
@@ -102,11 +103,25 @@ public enum ResultFormat
     }
   };
 
+  private final String name;
+
+  ResultFormat(final String name)
+  {
+    this.name = name;
+  }
+
   public abstract String contentType();
 
   public abstract Writer createFormatter(OutputStream outputStream, ObjectMapper jsonMapper) throws IOException;
 
-  interface Writer extends Closeable
+  @Override
+  @JsonValue
+  public String toString()
+  {
+    return name;
+  }
+
+  public interface Writer extends Closeable
   {
     /**
      * Start of the response, called once per writer.

sql/src/test/java/org/apache/druid/sql/http/ResultFormatTest.java

@@ -0,0 +1,70 @@
+/*
+ * 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.druid.sql.http;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import junitparams.JUnitParamsRunner;
+import junitparams.Parameters;
+import org.apache.druid.annotations.UsedByJUnitParamsRunner;
+import org.apache.druid.jackson.DefaultObjectMapper;
+import org.apache.druid.java.util.common.StringUtils;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.EnumSet;
+
+@RunWith(JUnitParamsRunner.class)
+public class ResultFormatTest
+{
+
+  private final ObjectMapper jsonMapper = new DefaultObjectMapper();
+
+  @Test
+  @Parameters(source = ResultFormatTypeProvider.class)
+  public void testSerde(ResultFormat target) throws JsonProcessingException
+  {
+    final String json = jsonMapper.writeValueAsString(target);
+    Assert.assertEquals(StringUtils.format("\"%s\"", target.toString()), json);
+    Assert.assertEquals(target, jsonMapper.readValue(json, ResultFormat.class));
+  }
+
+  @Test
+  public void testDeserializeWithDifferentCase() throws JsonProcessingException
+  {
+    Assert.assertEquals(ResultFormat.OBJECTLINES, jsonMapper.readValue("\"OBJECTLINES\"", ResultFormat.class));
+    Assert.assertEquals(ResultFormat.OBJECTLINES, jsonMapper.readValue("\"objectLines\"", ResultFormat.class));
+    Assert.assertEquals(ResultFormat.OBJECTLINES, jsonMapper.readValue("\"objectlines\"", ResultFormat.class));
+    Assert.assertEquals(ResultFormat.OBJECTLINES, jsonMapper.readValue("\"oBjEcTlInEs\"", ResultFormat.class));
+  }
+
+  public static class ResultFormatTypeProvider
+  {
+    @UsedByJUnitParamsRunner
+    public static Object[] provideResultFormats()
+    {
+      return EnumSet.allOf(ResultFormat.class)
+                    .stream()
+                    .map(format -> new Object[]{format})
+                    .toArray(Object[]::new);
+    }
+  }
+}