add correlation rule layer for events-correlation-engine

Signed-off-by: Subhobrata Dey <[email protected]>

Author: sbcd90

plugins/events-correlation-engine/src/main/java/org/opensearch/plugin/correlation/rules/model/CorrelationRule.java

@@ -41,6 +41,7 @@
  * }
  *
  * @opensearch.api
+ * @opensearch.experimental
  */
 public class CorrelationRule implements Writeable, ToXContentObject {
 

plugins/events-correlation-engine/src/main/java/org/opensearch/plugin/correlation/rules/transport/TransportIndexCorrelationRuleAction.java

@@ -82,7 +82,7 @@ protected void doExecute(Task task, IndexCorrelationRuleRequest request, ActionL
         asyncAction.start();
     }
 
-    class AsyncIndexCorrelationRuleAction {
+    private class AsyncIndexCorrelationRuleAction {
         private final IndexCorrelationRuleRequest request;
 
         private final ActionListener<IndexCorrelationRuleResponse> listener;

plugins/events-correlation-engine/src/main/java/org/opensearch/plugin/correlation/utils/CorrelationRuleIndices.java

@@ -64,7 +64,7 @@ public static String correlationRuleIndexMappings() throws IOException {
      * @throws IOException IOException
      */
     public void initCorrelationRuleIndex(ActionListener<CreateIndexResponse> actionListener) throws IOException {
-        if (!correlationRuleIndexExists()) {
+        if (correlationRuleIndexExists() == false) {
             CreateIndexRequest indexRequest = new CreateIndexRequest(CorrelationRule.CORRELATION_RULE_INDEX).mapping(
                 correlationRuleIndexMappings()
             ).settings(Settings.builder().put("index.hidden", true).build());