diff --git a/core/src/main/scala/org/apache/spark/scheduler/ExternalClusterManager.scala b/core/src/main/scala/org/apache/spark/scheduler/ExternalClusterManager.scala
index 6ca1f569b91d89855740c3d473e87b5d766b8911..d1ac7131baba5b93c9a9a67aad7433b88581406f 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/ExternalClusterManager.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/ExternalClusterManager.scala
@@ -18,14 +18,11 @@
 package org.apache.spark.scheduler
 
 import org.apache.spark.SparkContext
-import org.apache.spark.annotation.DeveloperApi
 
 /**
- * :: DeveloperApi ::
  * A cluster manager interface to plugin external scheduler.
  */
-@DeveloperApi
-trait ExternalClusterManager {
+private[spark] trait ExternalClusterManager {
 
   /**
    * Check if this cluster manager instance can create scheduler components