@GET
  @Path("{actionName}")
  @Produces(MediaType.TEXT_PLAIN)
  @ApiOperation(value = "Get the details of an action definition",
      nickname = "ActionService#getActionDefinition",
      response = ActionResponse.ActionResponseSwagger.class)
  @ApiImplicitParams({
      @ApiImplicitParam(name = QUERY_FIELDS, value = QUERY_FILTER_DESCRIPTION,
          defaultValue = "Actions/*",
          dataType = DATA_TYPE_STRING, paramType = PARAM_TYPE_QUERY)
  })
  @ApiResponses(value = {
      @ApiResponse(code = HttpStatus.SC_OK, message = MSG_SUCCESSFUL_OPERATION),
      @ApiResponse(code = HttpStatus.SC_UNAUTHORIZED, message = MSG_NOT_AUTHENTICATED),
      @ApiResponse(code = HttpStatus.SC_NOT_FOUND, message = MSG_RESOURCE_NOT_FOUND),
      @ApiResponse(code = HttpStatus.SC_INTERNAL_SERVER_ERROR, message = MSG_SERVER_ERROR)
  })
  public Response getActionDefinition(String body, @Context HttpHeaders headers, @Context UriInfo ui,
                             @ApiParam(required = true) @PathParam("actionName") String actionName) {

    return handleRequest(headers, body, ui, Request.Type.GET, createActionDefinitionResource(actionName));
  }
Handles: GET /actions/{actionName}
Get a specific action definition.

@param headers     http headers
@param ui          uri info
@param actionName action name
@return action definition instance representation
ambari-server/src/main/java/org/apache/ambari/server/api/services/ActionService.java