fixup! Bug

Author: jfreden

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/security/authc/support/mapper/ExpressionRoleMapping.java

@@ -237,7 +237,9 @@ public boolean isEnabled() {
      * Whether this mapping is an operator defined/read only role mapping
      */
     public boolean isReadOnly() {
-        return metadata.get(ExpressionRoleMapping.READ_ONLY_ROLE_MAPPING_METADATA_FLAG) instanceof Boolean readOnly ? readOnly : false;
+        return metadata != null && metadata.get(ExpressionRoleMapping.READ_ONLY_ROLE_MAPPING_METADATA_FLAG) instanceof Boolean readOnly
+            ? readOnly
+            : false;
     }
 
     @Override