Add spotless and checkstyle

build.gradle

@@ -13,6 +13,7 @@ plugins {
     id 'io.franzbecker.gradle-lombok' version '5.0.0'
     id 'com.github.johnrengelman.shadow' version '7.0.0'
     id 'me.champeau.gradle.japicmp' version '0.2.9' apply false
+    id 'com.diffplug.spotless' version '6.3.0' apply false
 }
 
 apply from: "$rootDir/gradle/ci-support.gradle"
@@ -22,6 +23,8 @@ subprojects {
     apply plugin: 'idea'
     apply plugin: 'io.franzbecker.gradle-lombok'
     apply from: "$rootDir/gradle/shading.gradle"
+    apply plugin: 'com.diffplug.spotless'
+    apply plugin: 'checkstyle'
 
     group = "org.testcontainers"
 
@@ -105,4 +108,39 @@ subprojects {
     dependencies {
         testImplementation 'ch.qos.logback:logback-classic:1.2.3'
     }
+
+    spotless {
+        enforceCheck false
+        java {
+            removeUnusedImports()
+            trimTrailingWhitespace()
+            endWithNewline()
+
+            prettier(['prettier': '2.5.1', 'prettier-plugin-java': '1.6.1'])
+                .config([
+                    'parser'    : 'java',
+                    'tabWidth'  : 4,
+                    'printWidth': 120
+                ])
+
+            importOrder('', 'java', 'javax', '\\#')
+        }
+        groovyGradle {
+            target '**/*.groovy'
+            greclipse('4.19.0')
+        }
+    }
+
+    checkstyle {
+        toolVersion = "9.3"
+        configFile = rootProject.file('config/checkstyle/checkstyle.xml')
+        checkstyleTest.enabled = false
+        checkstyleMain.enabled = false
+    }
+
+    tasks.whenTaskAdded {task ->
+        if (task.name.equals("checkstyleJarFileTest")) {
+            task.enabled = false
+        }
+    }
 }

config/checkstyle/checkstyle.xml

@@ -0,0 +1,47 @@
+<!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="SuppressionCommentFilter"/>
+        <module name="NeedBraces">
+            <property name="tokens"
+                      value="
+                      LITERAL_DO,
+                      LITERAL_ELSE,
+                      LITERAL_FOR,
+                      LITERAL_IF,
+                      LITERAL_WHILE,
+                      LITERAL_CASE,
+                      LITERAL_DEFAULT,
+                      LAMBDA,
+                      "
+            />
+            <property name="allowSingleLineStatement" value="true"/>
+        </module>
+        <module name="AvoidStaticImport">
+            <property name="excludes"
+                      value="
+                      io.restassured.RestAssured.*,
+                      org.assertj.core.api.Assertions.*,
+                      org.assertj.core.api.Assumptions.*,
+                      org.awaitility.Awaitility.*,
+                      org.hamcrest.Matchers.*,
+                      org.hamcrest.MatcherAssert.*,
+                      org.junit.Assert.*,
+                      org.junit.Assume.*,
+                      org.junit.jupiter.api.Assertions.*,
+                      org.mockito.Mockito.*,
+                      org.mockito.ArgumentMatchers.*,
+                      org.mockserver.model.HttpRequest.*,
+                      org.mockserver.model.HttpResponse.*,
+                      org.rnorth.ducttape.unreliables.Unreliables.*,
+                      org.rnorth.visibleassertions.VisibleAssertions.*,
+                      "
+            />
+        </module>
+        <module name="EmptyLineSeparator">
+            <property name="allowNoEmptyLineBetweenFields" value="false" />
+        </module>
+        <module name="OneStatementPerLineCheck"/>
+    </module>
+</module>

docs/contributing.md

@@ -8,6 +8,7 @@
     * follow the style, naming and structure conventions of the rest of the project.
     * make commits atomic and easy to merge.
     * when updating documentation, please see [our guidance for documentation contributions](contributing_docs.md).
+    * apply format running `./gradlew spotlessApply`
     * verify all tests are passing. Build the project with `./gradlew check` to do this.
     **N.B.** Gradle's Build Cache is enabled by default, but you can add `--no-build-cache` flag to disable it.
 

gradle/ci-support.gradle

@@ -17,7 +17,7 @@ task testMatrix {
     }
 }
 
-// If we're executing the `taskMatrix` task, disable tests and other slow tasks
+// If we're executing the `testMatrix` task, disable tests and other slow tasks
 //  so that we can get a result quickly.
 gradle.taskGraph.whenReady {
     if (it.hasTask(tasks.testMatrix)) {