@PUT @ApiIgnore // until documented
  @Path("{alias}")
  @Produces("text/plain")
  public Response updateCredential(String body, @Context HttpHeaders headers, @Context UriInfo ui,
                                   @PathParam("alias") String alias) {
    return handleRequest(headers, body, ui, Request.Type.PUT, createCredentialResource(alias));
  }
Handles: PUT /clusters/{cluster_name}/credentials/{alias}
Create a specific credential.

@param headers http headers
@param ui      uri info
@param alias   alias (or credential ID)
@return information regarding the created credential
ambari-server/src/main/java/org/apache/ambari/server/api/services/CredentialService.java