Add throw to prevent null ref exception

indexer-service-aws/src/main/java/org/opengroup/osdu/indexer/aws/util/HeadersInfoAwsImpl.java

@@ -15,9 +15,11 @@
 package org.opengroup.osdu.indexer.aws.util;
 
 import lombok.extern.java.Log;
+import org.apache.http.HttpStatus;
 import org.opengroup.osdu.core.api.DpsHeaders;
 import org.opengroup.osdu.is.core.model.SlbHeaders;
 import org.opengroup.osdu.is.core.provider.interfaces.util.IHeadersInfo;
+import org.opengroup.osdu.is.core.util.AppException;
 import org.opengroup.osdu.is.core.util.Preconditions;
 import org.springframework.stereotype.Component;
 import org.springframework.web.context.annotation.RequestScope;
@@ -44,12 +46,14 @@ public class HeadersInfoAwsImpl implements IHeadersInfo {
 
     /**
      * Get list of current headers
-     * @return DpsHeaders
+     * @return DpsHeaders headers
      */
     @Override
     public DpsHeaders getHeaders() {
         if (headersMap == null) {
             log.warning("Headers Map DpsHeaders is null");
+            // throw to prevent null reference exception below
+            throw new AppException(HttpStatus.SC_INTERNAL_SERVER_ERROR, "Invalid Headers", "Headers Map DpsHeaders is null");
         }
         DpsHeaders headers = this.getCoreServiceHeaders(headersMap.getHeaders());
         return headers;