Simplify Checkstyle configuration

* Move `checkstyle-conventions.gradle` content to the `build.gradle` since it is short enough
* Remove `checkstyle-header.txt` and its handling in favor of Spring Javaformat out-of-the box logic
* Upgrade to Gradle `8.5`
* Remove suppression for `Javadoc*` checks since it is handled by Spring Javaformat
* Leave only `MissingJavadocMethodCheck` exclusion from `SpringChecks` since all others really make sense for our code quality

build.gradle

@@ -6,7 +6,7 @@ buildscript {
 plugins {
 	id 'base'
 	id 'io.spring.dependency-management' version '1.1.4'
-	id "io.spring.javaformat" version "${javaFormatVersion}" apply false
+	id 'io.spring.javaformat' version "${javaFormatVersion}"
 	id 'com.github.spotbugs' version '6.0.4'
 	id 'com.google.protobuf' version '0.9.4' apply false
 }
@@ -66,8 +66,9 @@ configure(javaProjects) { subproject ->
 	apply plugin: 'java-library'
 	apply plugin: 'eclipse'
 	apply plugin: 'idea'
+	apply plugin: 'checkstyle'
+	apply plugin: 'io.spring.javaformat'
 	apply from: "${rootDir}/publish-maven.gradle"
-	apply from: "${rootDir}/gradle/checkstyle-conventions.gradle"
 
 	sourceSets {
 		test {
@@ -138,6 +139,22 @@ configure(javaProjects) { subproject ->
 
 	[compileJava, compileTestJava]*.options*.compilerArgs = ['-Xlint:all,-options,-processing', '-parameters']
 
+	checkstyle {
+		toolVersion = '10.3'
+		configDirectory = rootProject.file('etc/checkstyle')
+		ignoreFailures = true
+	}
+
+	dependencies {
+		// NOTE: We explicitly specify checkstyle dep before javaformat checkstyle due to antlr class mismatch
+		checkstyle("com.puppycrawl.tools:checkstyle:${checkstyle.toolVersion}")
+		checkstyle("io.spring.javaformat:spring-javaformat-checkstyle:${javaFormatVersion}")
+	}
+
+	tasks.named('checkFormatMain') {
+		exclude 'org/springframework/cloud/fn/object/detection/protos'
+	}
+
 	test {
 		maxHeapSize = '2g'
 		jvmArgs '-XX:+HeapDumpOnOutOfMemoryError'

etc/checkstyle/checkstyle-suppressions.xml

@@ -4,6 +4,6 @@
 		"https://checkstyle.org/dtds/suppressions_1_2.dtd">
 <suppressions>
 	<suppress files="package-info\.java" checks=".*" />
-	<suppress files="[\\/]test[\\/]" checks="RequireThis|AvoidStaticImport|Javadoc*" />
+	<suppress files="[\\/]test[\\/]" checks="RequireThis|AvoidStaticImport" />
 	<suppress files="Proto" checks=".*"/>
 </suppressions>

etc/checkstyle/checkstyle.xml

@@ -7,13 +7,7 @@
 		<property name="file"
 		          value="${config_loc}/checkstyle-suppressions.xml" />
 	</module>
-	<module name="com.puppycrawl.tools.checkstyle.checks.header.RegexpHeaderCheck">
-		<property name="headerFile" value="${config_loc}/checkstyle-header.txt" />
-		<property name="fileExtensions" value="java" />
-	</module>
 	<module name="io.spring.javaformat.checkstyle.SpringChecks">
-		<property name="excludes" value="io.spring.javaformat.checkstyle.check.SpringHeaderCheck" />
-		<property name="excludes" value="com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocPackageCheck" />
 		<property name="excludes" value="com.puppycrawl.tools.checkstyle.checks.javadoc.MissingJavadocMethodCheck" />
 	</module>
 	<module name="com.puppycrawl.tools.checkstyle.TreeWalker">

gradle/wrapper/gradle-wrapper.properties

@@ -1,7 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionSha256Sum=3e1af3ae886920c3ac87f7a91f816c0c7c436f276a6eefdb3da152100fef72ae
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
+distributionSha256Sum=9d926787066a081739e8200858338b4a69e837c3a821a33aca9db09dd4a41026
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME