runelite/config/checkstyle/checkstyle.xml

<?xml version="1.0"?>
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<!DOCTYPE module PUBLIC
	"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
	"https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
	<module name="TreeWalker">
		<module name="LeftCurly">
			<property name="option" value="nl"/>
			<!-- allow {} on anonymous classes and lambdas-->
			<property name="tokens" value="ANNOTATION_DEF, CLASS_DEF, CTOR_DEF, ENUM_CONSTANT_DEF, ENUM_DEF, INTERFACE_DEF, LITERAL_CASE, LITERAL_CATCH, LITERAL_DEFAULT, LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_SWITCH, LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, METHOD_DEF, STATIC_INIT"/>
		</module>
		<module name="RightCurly">
			<property name="option" value="alone"/>
		</module>
		<!-- require tabs for indenting - https://stackoverflow.com/a/28550141 -->
		<module name="RegexpSinglelineJava">
			<property name="format" value="^\t* "/>
			<property name="message" value="Indent must use tab characters"/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="RegexpSinglelineJava">
			<property name="format" value="[^\s]\s+$"/>
			<property name="message" value="No trailing whitespace"/>
			<property name="ignoreComments" value="true"/>
		</module>
		<module name="WhitespaceAround">
			<property name="allowEmptyTypes" value="true"/>
		</module>
		<module name="WhitespaceAfter">
			<property name="tokens" value="COMMA"/>
		</module>
		<module name="UnusedImports"/>
	</module>
	<module name="RegexpMultiline">
		<property name="format" value="else[ \t]*[\r\n]+[ \t]*if"/>
		<property name="message" value="Newline should not be between else and if"/>
	</module>
</module>