code: ///////////////////////////////////////////////////////////////////////////////////////////////
  // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
  // Copyright (C) 2001-2023 the original author or authors.
  //
  // This library is free software; you can redistribute it and/or
  // modify it under the terms of the GNU Lesser General Public
  // License as published by the Free Software Foundation; either
  // version 2.1 of the License, or (at your option) any later version.
  //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle;
  
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Inherited;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;
  
  /**
   * This annotation means that the check contains file-related context and therefore
   * cannot be used from the others threads at the same time.
   * This annotation should be used when the check holds a thread-unsafe state.
   * Checker guarantees that the whole file processed inside the same thread.
   * Checker guarantees that the whole file processed with the same check instance.
   * Checker guarantees that each check instance processes only one file at the same time.
   * Checker guarantees that all check instances have equal (but not the same) configuration.
   * It means, that if a check holds a property of type "array of strings",
   * the property value will not be shared across check instances.
   * Instead, each check instance will hold its own array instance.
   * Checker does not guarantee that each file will have its own thread -
   * there might be a list of files, which will be executed on the same thread.
   * Checker does not guarantee that each file will have its own check instance -
   * there might be a list of files, which will be checked by the same instance.
   * Note: Checks with such annotation will be executed in mode how all Checks worked
   * before MT mode is introduced.
   *
   * @noinspection ClassIndependentOfModule
   * @noinspectionreason ClassIndependentOfModule - we keep this annotation at top level by design
   */
  @Retention(RetentionPolicy.RUNTIME)
  @Target(ElementType.TYPE)
  @Inherited
  public @interface FileStatefulCheck {
  
      // this annotation does not have properties
  
  }
  