checkstyle.xml

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

<!--
    Aether Datafixers Checkstyle Configuration
    Based on Google Java Style with project-specific adjustments
-->
<module name="Checker">
    <property name="charset" value="UTF-8"/>
    <property name="severity" value="warning"/>
    <property name="fileExtensions" value="java"/>

    <!-- Suppress checks for generated code (uncomment when checkstyle-suppressions.xml exists)
    <module name="SuppressionFilter">
        <property name="file" value="${config_loc}/checkstyle-suppressions.xml"/>
        <property name="optional" value="true"/>
    </module>
    -->

    <!-- File length -->
    <module name="FileLength">
        <property name="max" value="3000"/>
        <property name="severity" value="warning"/>
    </module>

    <!-- No trailing whitespace -->
    <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."/>
        <property name="severity" value="info"/>
    </module>

    <!-- Newline at end of file -->
    <module name="NewlineAtEndOfFile">
        <property name="severity" value="info"/>
    </module>

    <!-- Line length - must be under Checker, not TreeWalker -->
    <module name="LineLength">
        <property name="max" value="300"/>
        <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
    </module>

    <module name="TreeWalker">
        <!-- Naming conventions -->
        <module name="PackageName">
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
        </module>
        <module name="TypeName">
            <property name="format" value="^[A-Z][a-zA-Z0-9]*$"/>
        </module>
        <module name="MethodName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="ConstantName">
            <property name="format" value="^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$|^log(ger)?$"/>
        </module>
        <module name="LocalVariableName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="MemberName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="ParameterName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="StaticVariableName">
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
        </module>
        <module name="ClassTypeParameterName">
            <property name="format" value="^[A-Z][A-Z0-9]*$"/>
        </module>
        <module name="MethodTypeParameterName">
            <property name="format" value="^[A-Z][A-Z0-9]*$"/>
        </module>
        <module name="InterfaceTypeParameterName">
            <property name="format" value="^[A-Z][A-Z0-9]*$"/>
        </module>

        <!-- Import checks -->
        <module name="AvoidStarImport">
            <property name="severity" value="warning"/>
        </module>
        <module name="RedundantImport"/>
        <module name="UnusedImports"/>
        <module name="IllegalImport">
            <property name="illegalPkgs" value="sun,com.sun"/>
        </module>

        <!-- Whitespace -->
        <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="NoWhitespaceBefore"/>
        <module name="GenericWhitespace"/>
        <module name="MethodParamPad"/>
        <module name="ParenPad"/>
        <module name="TypecastParenPad"/>

        <!-- Braces -->
        <module name="NeedBraces">
            <property name="allowSingleLineStatement" value="false"/>
        </module>
        <module name="LeftCurly"/>

        <!-- Block checks -->
        <module name="EmptyBlock">
            <property name="option" value="TEXT"/>
            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
        </module>
        <module name="AvoidNestedBlocks"/>

        <!-- Coding -->
        <module name="EmptyStatement"/>
        <module name="EqualsHashCode"/>
        <module name="IllegalInstantiation"/>
        <module name="SimplifyBooleanExpression"/>
        <module name="SimplifyBooleanReturn"/>
        <module name="StringLiteralEquality"/>
        <module name="NestedForDepth">
            <property name="max" value="3"/>
        </module>
        <module name="NestedIfDepth">
            <property name="max" value="4"/>
        </module>
        <module name="NestedTryDepth">
            <property name="max" value="2"/>
        </module>
        <module name="NoClone"/>
        <module name="NoFinalizer"/>
        <module name="OneStatementPerLine"/>
        <module name="PackageDeclaration"/>
        <module name="DefaultComesLast"/>
        <module name="FallThrough"/>
        <module name="MultipleVariableDeclarations"/>
        <module name="UnnecessaryParentheses"/>
        <module name="UnnecessarySemicolonAfterOuterTypeDeclaration"/>
        <module name="UnnecessarySemicolonAfterTypeMemberDeclaration"/>
        <module name="UnnecessarySemicolonInEnumeration"/>
        <module name="UnnecessarySemicolonInTryWithResources"/>

        <!-- Design -->
        <module name="OneTopLevelClass"/>
        <module name="InterfaceIsType"/>
        <module name="MutableException"/>

        <!-- Miscellaneous -->
        <module name="ArrayTypeStyle"/>
        <module name="UpperEll"/>
        <module name="OuterTypeFilename"/>
        <module name="AvoidEscapedUnicodeCharacters">
            <property name="allowEscapesForControlCharacters" value="true"/>
            <property name="allowByTailComment" value="true"/>
            <property name="allowNonPrintableEscapes" value="true"/>
        </module>

        <!-- Annotations -->
        <module name="AnnotationLocation">
            <property name="allowSamelineMultipleAnnotations" value="false"/>
            <property name="allowSamelineSingleParameterlessAnnotation" value="true"/>
            <property name="allowSamelineParameterizedAnnotation" value="false"/>
        </module>
        <module name="MissingOverride"/>

        <!-- Javadoc - relaxed for now -->
        <module name="InvalidJavadocPosition"/>
        <module name="JavadocMethod">
            <property name="severity" value="info"/>
            <property name="accessModifiers" value="public"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
        </module>
        <module name="JavadocType">
            <property name="severity" value="info"/>
            <property name="scope" value="public"/>
        </module>

        <!-- Modifier order -->
        <module name="ModifierOrder"/>

        <!-- Indentation: 4 spaces -->
        <module name="Indentation">
            <property name="basicOffset" value="4"/>
            <property name="braceAdjustment" value="0"/>
            <property name="caseIndent" value="4"/>
            <property name="lineWrappingIndentation" value="8"/>
            <property name="tabWidth" value="4"/>
        </module>
    </module>
</module>