Adding spotless plugin to project build.gradle.

Signed-off-by: Mitchell Gale <Mitchell.Gale@improving.com>

Remove commented out spotless changes.

Signed-off-by: Mitchell Gale <Mitchell.Gale@improving.com>

Adding Spotless to DEVELOPER_GUIDE.rst

Signed-off-by: Mitchell Gale <Mitchell.Gale@improving.com>

Added Google Java format to spotless.

Signed-off-by: Mitchell Gale <Mitchell.Gale@improving.com>

Update DEVELOPER_GUIDE.rst

Co-authored-by: Yury-Fridlyand <yury.fridlyand@improving.com>

DEVELOPER_GUIDE.rst

@@ -113,8 +113,8 @@ Note that missing license header will be detected by Gradle license plugin and f
 Making Code Changes
 ===================
 
-Project Strucure
-----------------
+Project Structure
+-----------------
 
 The plugin codebase is in standard layout of Gradle project::
 
@@ -226,6 +226,10 @@ Most of the time you just need to run ./gradlew build which will make sure you p
      - Build plugin by run all tasks above (this takes time).
    * - ./gradlew pitest
      - Run PiTest mutation testing (see more info in `#1204 <https://github.com/opensearch-project/sql/pull/1204>`_)
+   * - ./gradlew spotlessCheck
+     - Runs Spotless to check for code style.
+   * - ./gradlew spotlessApply
+     - Automatically apply spotless code style changes.
 
 For integration test, you can use ``-Dtests.class`` “UT full path” to run a task individually. For example ``./gradlew :integ-test:integTest -Dtests.class="*QueryIT"``.
 

build.gradle

@@ -65,6 +65,7 @@ plugins {
     id 'checkstyle'
     id "io.freefair.lombok" version "6.4.0"
     id 'jacoco'
+    id 'com.diffplug.spotless' version '6.19.0'
 }
 
 // import versions defined in https://github.com/opensearch-project/OpenSearch/blob/main/buildSrc/src/main/java/org/opensearch/gradle/OpenSearchJavaPlugin.java#L94
@@ -79,6 +80,20 @@ repositories {
     maven { url 'https://jitpack.io' }
 }
 
+spotless {
+    java {
+        target fileTree('.') {
+            include '**/*.java'
+            exclude '**/build/**', '**/build-*/**'
+        }
+        importOrder()
+        removeUnusedImports()
+        trimTrailingWhitespace()
+        endWithNewline()
+        googleJavaFormat()
+    }
+}
+
 allprojects {
     version = opensearch_version.tokenize('-')[0] + '.0'
     if (buildVersionQualifier) {