checkstyle: 8.0 -> 8.12 (#1369)

This commit also merges new changes to checkstyle.xml and fixes new checkstyle
warnings related to Javadocs.

2 files changed, 72 insertions, 32 deletions

diff --git a/buildscripts/checkstyle.xml b/buildscripts/checkstyle.xml
index bfdc314f..50b146e7 100644
--- a/buildscripts/checkstyle.xml
+++ b/buildscripts/checkstyle.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!DOCTYPE module PUBLIC
-          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
-          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+          "https://checkstyle.org/dtds/configuration_1_3.dtd">
 
 <!--
     Checkstyle configuration that checks the Google coding conventions from Google Java Style
@@ -29,16 +29,18 @@
     <property name="fileExtensions" value="java, properties, xml"/>
     <!-- Checks for whitespace                               -->
     <!-- See http://checkstyle.sf.net/config_whitespace.html -->
-        <module name="FileTabCharacter">
-            <property name="eachLine" value="true"/>
-        </module>
+    <module name="FileTabCharacter">
+        <property name="eachLine" value="true"/>
+    </module>
 
     <module name="TreeWalker">
         <module name="OuterTypeFilename"/>
         <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."/>
+            <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"/>
@@ -55,20 +57,23 @@
         <module name="NoLineWrap"/>
         <module name="EmptyBlock">
             <property name="option" value="TEXT"/>
-            <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
+            <property name="tokens"
+             value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
         </module>
         <module name="NeedBraces"/>
-        <module name="LeftCurly">
-            <property name="maxLineLength" value="100"/>
-        </module>
+        <module name="LeftCurly"/>
         <module name="RightCurly">
             <property name="id" value="RightCurlySame"/>
-            <property name="tokens" value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_DO"/>
+            <property name="tokens"
+             value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE,
+                    LITERAL_DO"/>
         </module>
         <module name="RightCurly">
             <property name="id" value="RightCurlyAlone"/>
             <property name="option" value="alone"/>
-            <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT, INSTANCE_INIT"/>
+            <property name="tokens"
+             value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT,
+                    INSTANCE_INIT"/>
         </module>
         <module name="WhitespaceAround">
             <property name="allowEmptyConstructors" value="true"/>
@@ -77,14 +82,14 @@
             <property name="allowEmptyLoops" value="true"/>
             <message key="ws.notFollowed"
              value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
-             <message key="ws.notPreceded"
+            <message key="ws.notPreceded"
              value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
         </module>
         <module name="OneStatementPerLine"/>
         <module name="MultipleVariableDeclarations"/>
         <module name="ArrayTypeStyle"/>
-        <!-- This rule conflicts with Error Prone's exhaustiveness checking. -->
-	    <!-- <module name="MissingSwitchDefault"/> -->
+        <!-- <!-\- This rule conflicts with Error Prone's exhaustiveness checking. -\-> -->
+        <!-- <module name="MissingSwitchDefault"/> -->
         <module name="FallThrough"/>
         <module name="UpperEll"/>
         <module name="ModifierOrder"/>
@@ -101,6 +106,23 @@
             <property name="tokens" value="COMMA"/>
             <property name="option" value="EOL"/>
         </module>
+        <module name="SeparatorWrap">
+            <!-- ELLIPSIS is EOL until https://github.com/google/styleguide/issues/258 -->
+            <property name="id" value="SeparatorWrapEllipsis"/>
+            <property name="tokens" value="ELLIPSIS"/>
+            <property name="option" value="EOL"/>
+        </module>
+        <module name="SeparatorWrap">
+            <!-- ARRAY_DECLARATOR is EOL until https://github.com/google/styleguide/issues/259 -->
+            <property name="id" value="SeparatorWrapArrayDeclarator"/>
+            <property name="tokens" value="ARRAY_DECLARATOR"/>
+            <property name="option" value="EOL"/>
+        </module>
+        <module name="SeparatorWrap">
+            <property name="id" value="SeparatorWrapMethodRef"/>
+            <property name="tokens" value="METHOD_REF"/>
+            <property name="option" value="nl"/>
+        </module>
         <module name="PackageName">
             <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
             <message key="name.invalidPattern"
@@ -120,6 +142,11 @@
             <message key="name.invalidPattern"
              value="Parameter name ''{0}'' must match pattern ''{1}''."/>
         </module>
+        <module name="LambdaParameterName">
+            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+            <message key="name.invalidPattern"
+                     value="Lambda parameter name ''{0}'' must match pattern ''{1}''."/>
+        </module>
         <module name="CatchParameterName">
             <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
             <message key="name.invalidPattern"
@@ -150,11 +177,11 @@
         <module name="GenericWhitespace">
             <message key="ws.followed"
              value="GenericWhitespace ''{0}'' is followed by whitespace."/>
-             <message key="ws.preceded"
+            <message key="ws.preceded"
              value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
-             <message key="ws.illegalFollow"
+            <message key="ws.illegalFollow"
              value="GenericWhitespace ''{0}'' should followed by whitespace."/>
-             <message key="ws.notPreceded"
+            <message key="ws.notPreceded"
              value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
         </module>
         <!-- <!-\- Checkstyle indentation rules conflict with google-java-format: -\-> -->
@@ -171,20 +198,30 @@
             <property name="allowedAbbreviationLength" value="1"/>
         </module>
         <module name="OverloadMethodsDeclarationOrder"/>
+        <!-- <!-\- Many unit tests define all variables at the start of the method. -\-> -->
+        <!-- <module name="VariableDeclarationUsageDistance"/> -->
         <module name="CustomImportOrder">
             <property name="sortImportsInGroupAlphabetically" value="true"/>
             <property name="separateLineBetweenGroups" value="true"/>
             <property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
         </module>
         <module name="MethodParamPad"/>
+        <module name="NoWhitespaceBefore">
+            <property name="tokens"
+             value="COMMA, SEMI, POST_INC, POST_DEC, DOT, ELLIPSIS, METHOD_REF"/>
+            <property name="allowLineBreaks" value="true"/>
+        </module>
         <module name="ParenPad"/>
         <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 "/>
+            <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="AnnotationLocation">
             <property name="id" value="AnnotationLocationMostCases"/>
-            <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
+            <property name="tokens"
+             value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
         </module>
         <module name="AnnotationLocation">
             <property name="id" value="AnnotationLocationVariables"/>
@@ -194,12 +231,14 @@
         <module name="NonEmptyAtclauseDescription"/>
         <module name="JavadocTagContinuationIndentation"/>
         <module name="SummaryJavadoc">
-            <property name="forbiddenSummaryFragments" value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
+            <property name="forbiddenSummaryFragments"
+             value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
         </module>
         <module name="JavadocParagraph"/>
         <module name="AtclauseOrder">
             <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
-            <property name="target" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
+            <property name="target"
+             value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
         </module>
         <module name="JavadocMethod">
             <property name="scope" value="public"/>
@@ -207,9 +246,11 @@
             <property name="allowMissingThrowsTags" value="true"/>
             <property name="allowMissingReturnTag" value="true"/>
             <property name="minLineCount" value="2"/>
-            <!-- Too restrictive for tests -->
-            <!-- <property name="allowedAnnotations" value="Override, Test"/-->
-            <property name="allowedAnnotations" value="Override, Test, Before, After, BeforeClass, AfterClass, Setup, TearDown"/>
+            <!-- <!-\- Too restrictive for tests -\-> -->
+            <!-- <property name="allowedAnnotations" value="Override, Test"/ -->
+            <property name="allowedAnnotations"
+                      value="Override, Test, Before, After, BeforeClass, AfterClass, Setup,
+                             TearDown"/>
             <property name="allowThrowsTagsForSubclasses" value="true"/>
         </module>
         <module name="MethodName">
@@ -218,20 +259,19 @@
              value="Method name ''{0}'' must match pattern ''{1}''."/>
         </module>
         <module name="SingleLineJavadoc">
-            <!-- Wrong interpretation of the style guide; -->
-            <!-- <property name="ignoreInlineTags" value="false"/-->
+            <!-- <!-\- Wrong interpretation of the style guide; -\-> -->
+            <!-- <property name="ignoreInlineTags" value="false"/ -->
         </module>
         <module name="EmptyCatchBlock">
             <property name="exceptionVariableName" value="expected"/>
         </module>
         <module name="CommentsIndentation"/>
-        <module name="FileContentsHolder"/>
         <module name="SuppressWarningsHolder"/>
         <module name="ImportControl">
             <property name="file" value="${rootDir}/buildscripts/import-control.xml"/>
             <property name="path" value="^.*[\\/]src[\\/]main[\\/]java[\\/].*$"/>
         </module>
+        <module name="SuppressionCommentFilter"/>
     </module>
-    <module name="SuppressionCommentFilter"/>
     <module name="SuppressWarningsFilter"/>
 </module>
diff --git a/buildscripts/kokoro/linux_presubmit.sh b/buildscripts/kokoro/linux_presubmit.sh
index 327d310c..bb1281b4 100755
--- a/buildscripts/kokoro/linux_presubmit.sh
+++ b/buildscripts/kokoro/linux_presubmit.sh
@@ -64,8 +64,8 @@ case "$TASK" in
     ./gradlew clean assemble -PcheckerFramework=true
     ;;
   "CHECK_EXAMPLES_LICENSE")
-    curl -L -o checkstyle-8.0-all.jar https://github.com/checkstyle/checkstyle/releases/download/checkstyle-8.0/checkstyle-8.0-all.jar
-    java -DrootDir=. -jar checkstyle-8.0-all.jar -c buildscripts/checkstyle.xml examples/src/
+    curl -L -o checkstyle-8.12-all.jar https://github.com/checkstyle/checkstyle/releases/download/checkstyle-8.12/checkstyle-8.12-all.jar
+    java -DrootDir=. -jar checkstyle-8.12-all.jar -c buildscripts/checkstyle.xml examples/src/
     ;;
   "CHECK_EXAMPLES_FORMAT")
     curl -L -o google-java-format-1.5-all-deps.jar \