src/jdk.vm.ci/share/classes/jdk.vm.ci.code/src/jdk/vm/ci/code/ReferenceMap.java

*** 20,26 ****
--- 20,31 ----
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  package jdk.vm.ci.code;
  
+ /**
+  * Marker type for an object containing information about where the object references are in machine
+  * state (e.g., registers or stack locations). This is typically associated with an execution point
+  * in compiled code.
+  */
  public abstract class ReferenceMap {
  }