private ExtensionLinkRequest getRequest(Map<String, Object> properties) {
    return new ExtensionLinkRequest(
        (String) properties.get(LINK_ID_PROPERTY_ID),
        (String) properties.get(STACK_NAME_PROPERTY_ID),
        (String) properties.get(STACK_VERSION_PROPERTY_ID),
        (String) properties.get(EXTENSION_NAME_PROPERTY_ID),
        (String) properties.get(EXTENSION_VERSION_PROPERTY_ID));
  }
The property ids for a ExtensionLink resource.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/ExtensionLinkResourceProvider.java