checkstyle.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
  "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
  "https://checkstyle.org/dtds/configuration_1_3.dtd">

<module name="Checker">
  <property name="charset" value="UTF-8"/>

  <module name="SuppressionFilter">
    <property name="file" value="${config_loc}/suppressions.xml"/>
    <property name="optional" value="true"/>
  </module>

  <!-- Avoid choking on module-info.java -->
  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

  <!-- General formatting -->
  <module name="FileTabCharacter"/>
  <module name="RegexpSingleline">
    <property name="format" value="\s+$"/>
    <property name="message" value="trailing whitespace"/>
  </module>

  <!-- Prohibit consecutive empty lines (except the lines after package/import) -->
  <module name="RegexpMultiline">
    <property name="format" value="\n *(?!package )(?!import )[^\n]+\n{3,}"/>
    <property name="message" value="two or more consecutive empty lines"/>
  </module>
  <module name="NewlineAtEndOfFile"/>

  <module name="TreeWalker">
    <!-- Files -->
    <module name="OneTopLevelClass"/>
    <module name="OuterTypeFilename"/>

    <!-- Imports -->
    <module name="AvoidStarImport"/>
    <module name="UnusedImports">
      <property name="processJavadoc" value="true"/>
    </module>
    <module name="CustomImportOrder">
      <property name="thirdPartyPackageRegExp" value=".*"/>
      <property name="specialImportsRegExp" value="com.apple"/>
      <property name="sortImportsInGroupAlphabetically" value="true"/>
      <property name="separateLineBetweenGroups" value="true"/>
      <property name="customImportOrderRules" value="SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE###STANDARD_JAVA_PACKAGE###STATIC"/>
    </module>

    <!-- Modifiers -->
    <module name="ModifierOrder"/>
    <module name="RedundantModifier"/>

    <!-- Whitespace -->
    <module name="GenericWhitespace"/>
    <module name="EmptyForInitializerPad"/>
    <module name="EmptyForIteratorPad"/>
    <module name="MethodParamPad"/>
    <module name="ParenPad"/>
    <module name="TypecastParenPad"/>
    <module name="NoWhitespaceBefore"/>
    <module name="NoWhitespaceAfter"/>
    <module name="WhitespaceAround">
      <property name="allowEmptyConstructors" value="true"/>
      <property name="allowEmptyMethods" value="true"/>
      <property name="allowEmptyTypes" value="true"/>
      <property name="allowEmptyLoops" value="true"/>
    </module>
    <module name="WhitespaceAfter"/>
    <module name="SingleSpaceSeparator"/>

    <!-- Blocks -->
    <module name="NeedBraces">
      <property name="allowSingleLineStatement" value="true"/>
    </module>
    <module name="LeftCurly"/>
    <module name="RightCurly">
      <property name="tokens" value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY"/>
    </module>
    <module name="AvoidNestedBlocks">
      <property name="allowInSwitchCase" value="true"/>
    </module>

    <!-- Javadocs -->
    <module name="JavadocMethod">
      <property name="accessModifiers" value="public"/>
      <property name="allowMissingParamTags" value="true"/>
      <property name="allowMissingReturnTag" value="true"/>
    </module>
    <module name="NonEmptyAtclauseDescription"/>
    <module name="AtclauseOrder"/>
    <module name="JavadocStyle">
      <property name="scope" value="public"/>
      <property name="tokens" value="ANNOTATION_DEF, ANNOTATION_FIELD_DEF, CLASS_DEF, CTOR_DEF, ENUM_DEF, INTERFACE_DEF, METHOD_DEF"/>
    </module>
    <module name="MissingJavadocMethod">
      <property name="allowMissingPropertyJavadoc" value="true"/>
    </module>

    <!-- Misc -->
    <module name="UpperEll"/>
    <module name="ArrayTypeStyle"/>
    <module name="EmptyStatement"/>
    <module name="EmptyLineSeparator">
      <property name="allowNoEmptyLineBetweenFields" value="true"/>
    </module>
  </module>
</module>