@PUT
  @Path("{settingName}")
  @Produces(MediaType.TEXT_PLAIN)
  @ApiOperation(value = "Updates a setting")
  @ApiImplicitParams({
    @ApiImplicitParam(dataType = SETTING_REQUEST_TYPE, paramType = PARAM_TYPE_BODY, required = true)
  })
  @ApiResponses({
    @ApiResponse(code = HttpStatus.SC_OK, message = MSG_SUCCESSFUL_OPERATION),
    @ApiResponse(code = HttpStatus.SC_NOT_FOUND, message = MSG_RESOURCE_NOT_FOUND),
    @ApiResponse(code = HttpStatus.SC_UNAUTHORIZED, message = MSG_NOT_AUTHENTICATED),
    @ApiResponse(code = HttpStatus.SC_FORBIDDEN, message = MSG_PERMISSION_DENIED),
    @ApiResponse(code = HttpStatus.SC_INTERNAL_SERVER_ERROR, message = MSG_SERVER_ERROR),
  })
  public Response updateSetting(String body, @Context HttpHeaders headers, @Context UriInfo ui,
    @ApiParam(value = "setting name", required = true) @PathParam("settingName") String settingName
  ) {
    ResourceInstance resource = createSettingResource(settingName);
    return handleRequest(headers, body, ui, Request.Type.PUT, resource);
  }
Handles: PUT /settings/{settingName}
Update a specific setting.

@param headers      http headers
@param ui           uri info
@param settingName  setting name

@return information regarding the updated setting
ambari-server/src/main/java/org/apache/ambari/server/api/services/SettingService.java