code: private static CreateRequestType checkType(final FormItemList formItemList,
  			final CreateResponse createResponse) {
  		final String sType = formItemList
  				.getField(ProtocolConstants.Parameters.Create.TYPE);
  		if (sType != null) {
  			if (CreateRequestType.USER.getIdentifier().equals(sType)) {
  				return CreateRequestType.USER;
  			} else if (CreateRequestType.FOLLOW.getIdentifier().equals(sType)) {
  				return CreateRequestType.FOLLOW;
  			} else if (CreateRequestType.STATUS_UPDATE.getIdentifier().equals(
  					sType)) {
  				return CreateRequestType.STATUS_UPDATE;
  			}
  
  			createResponse.typeInvalid(sType);
  		} else {
  			createResponse.typeMissing();
  		}
  
  		return null;
  	}
docs: check if the request contains a valid create request type
  
  @param formItemList
  form item list
  @param createResponse
  create response object
  @return create request type<br>
  <b>null</b> if the create request type is invalid