code: private boolean processingAllowed(final String prefix, final String variable, final TemplateReplacementContext context) {
  		return (PREFIX.equals(prefix) && !StringUtils.isEmpty(variable) && context instanceof MailTemplateReplacementContext);
  	}
docs: Checks whether processing is allowed.
  
  @param prefix  variable prefix
  @param context {@link TemplateReplacementContext}
  @return {@code boolean} flag