checkstyle.xml

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

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

  <property name="fileExtensions" value="java, properties, xml"/>

  <!-- Excludes all 'module-info.java' files              -->
  <!-- See https://checkstyle.org/config_filefilters.html -->
  <module name="BeforeExecutionExclusionFileFilter">
    <property name="fileNamePattern" value="module\-info\.java$"/>
  </module>

  <module name="SuppressionFilter">
    <property name="file" value="checkstyleSuppression.xml"/>
    <property name="optional" value="false"/>
  </module>

  <!-- Checks for whitespace                               -->
  <!-- See http://checkstyle.sourceforge.net/config_whitespace.html -->
  <module name="FileTabCharacter">
    <property name="eachLine" value="true"/>
  </module>

  <!-- Checks whether files end with a new line.                        -->
  <!-- See http://checkstyle.sourceforge.net/config_misc.html#NewlineAtEndOfFile -->
  <module name="NewlineAtEndOfFile">
    <!--  Not checking properties files for newlines (yet).  -->
    <property name="fileExtensions" value="java, xml"/>
  </module>

  <!-- Checks that property files contain the same keys.         -->
  <!-- See http://checkstyle.sourceforge.net/config_misc.html#Translation -->
  <module name="Translation"/>

  <!-- Checks for Size Violations.                    -->
  <!-- See http://checkstyle.sourceforge.net/config_sizes.html -->
  <module name="FileLength"/>

  <!-- Miscellaneous other checks.                   -->
  <!-- See http://checkstyle.sourceforge.net/config_misc.html -->
  <module name="RegexpSingleline">
    <property name="format" value="\s+$"/>
    <property name="minimum" value="0"/>
    <property name="maximum" value="0"/>
    <property name="message" value="Line has trailing spaces."/>
  </module>

  <module name="TreeWalker">
    <module name="OuterTypeFilename">
      <property name="severity" value="warning"/>
    </module>
    <module name="IllegalTokenText">
      <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
      <property name="format"
                value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
      <property name="message"
                value="Consider using special escape sequence instead of octal value or Unicode escaped value."/>
    </module>
    <module name="AvoidEscapedUnicodeCharacters">
      <property name="allowEscapesForControlCharacters" value="true"/>
      <property name="allowByTailComment" value="true"/>
      <property name="allowNonPrintableEscapes" value="true"/>
    </module>

    <module name="NoLineWrap"/>

    <!-- Checks for Naming Conventions.                  -->
    <!-- See http://checkstyle.sourceforge.net/config_naming.html -->
    <module name="PackageName"/>
    <module name="TypeName"/>

    <!-- Checks for whitespace                               -->
    <!-- See http://checkstyle.sourceforge.net/config_whitespace.html -->
    <module name="GenericWhitespace"/>
    <module name="MethodParamPad"/>
    <module name="TypecastParenPad"/>
    <module name="NoWhitespaceAfter"/>
    <module name="NoWhitespaceBefore"/>

    <module name="OperatorWrap">
      <property name="option" value="NL"/>
      <property name="tokens"
                value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR,
                 LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR, METHOD_REF "/>
    </module>
    <module name="ParenPad"/>
    <module name="TypecastParenPad"/>
    <module name="WhitespaceAfter"/>
    <module name="WhitespaceAround"/>


    <!-- Checks for imports                              -->
    <!-- See http://checkstyle.sourceforge.net/config_import.html -->
    <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
    <module name="RedundantImport"/>
    <module name="UnusedImports">
      <property name="processJavadoc" value="false"/>
    </module>

    <!-- Modifier Checks                                    -->
    <!-- See http://checkstyle.sourceforge.net/config_modifiers.html -->
    <module name="ModifierOrder"/>

    <!-- Checks for blocks. You know, those {}'s         -->
    <!-- See http://checkstyle.sourceforge.net/config_blocks.html -->
    <module name="AvoidNestedBlocks"/>
    <module name="LeftCurly"/>
    <module name="NeedBraces"/>
    <module name="RightCurly"/>

  </module>

</module>