@GET
  @Path("{userName}")
  @Produces("text/plain")
  @ApiOperation(value = "Get single user", response = UserResponse.UserResponseSwagger.class)
  @ApiImplicitParams({
      @ApiImplicitParam(name = QUERY_FIELDS, value = QUERY_FILTER_DESCRIPTION, dataType = DATA_TYPE_STRING, paramType = PARAM_TYPE_QUERY, defaultValue = USER_RESOURCE_CATEGORY + "/*"),
  })
  @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 getUser(String body, @Context HttpHeaders headers, @Context UriInfo ui,
                          @ApiParam(value = "user name", required = true) @PathParam("userName") String userName) {
    return handleRequest(headers, body, ui, Request.Type.GET, createUserResource(userName));
  }
Gets a single user.
Handles: GET /users/{username} requests

@param headers  http headers
@param ui       uri info
@param userName the username
@return information regarding the created user
ambari-server/src/main/java/org/apache/ambari/server/api/services/users/UserService.java