Add Spring specific HideUtilityClassConstructor

Add a Spring variant of `HideUtilityClassConstructor` that will
automatically bypass checks for `@SpringApplication` and
`@Configuration` classes.

Closes gh-74

Author: philwebb

spring-javaformat/spring-javaformat-checkstyle/src/main/java/io/spring/javaformat/checkstyle/check/SpringHideUtilityClassConstructor.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.javaformat.checkstyle.check;
+
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import com.puppycrawl.tools.checkstyle.api.DetailAST;
+import com.puppycrawl.tools.checkstyle.checks.design.HideUtilityClassConstructorCheck;
+import com.puppycrawl.tools.checkstyle.utils.AnnotationUtil;
+
+/**
+ * Extension to {@link HideUtilityClassConstructorCheck} that doesn't fail certain common
+ * Spring patterns.
+ *
+ * @author Phillip Webb
+ */
+public class SpringHideUtilityClassConstructor extends HideUtilityClassConstructorCheck {
+
+	private static final Set<String> BYPASS_ANNOTATIONS;
+	static {
+		Set<String> annotations = new LinkedHashSet<>();
+		annotations.add("org.springframework.context.annotation.Configuration");
+		annotations.add("org.springframework.boot.autoconfigure.SpringBootApplication");
+		annotations.add("org.springframework.boot.autoconfigure.EnableAutoConfiguration");
+		Set<String> shortNames = annotations.stream()
+				.map((name) -> name.substring(name.lastIndexOf(".") + 1))
+				.collect(Collectors.toSet());
+		annotations.addAll(shortNames);
+		BYPASS_ANNOTATIONS = Collections.unmodifiableSet(annotations);
+	}
+
+	@Override
+	public void visitToken(DetailAST ast) {
+		if (!isBypassed(ast)) {
+			super.visitToken(ast);
+		}
+	}
+
+	private boolean isBypassed(DetailAST ast) {
+		for (String bypassAnnotation : BYPASS_ANNOTATIONS) {
+			if (AnnotationUtil.containsAnnotation(ast, bypassAnnotation)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+}

spring-javaformat/spring-javaformat-checkstyle/src/main/resources/io/spring/javaformat/checkstyle/spring-checkstyle.xml

@@ -42,7 +42,7 @@
 		<!-- Class Design -->
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.FinalClassCheck" />
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.InterfaceIsTypeCheck" />
-		<module name="com.puppycrawl.tools.checkstyle.checks.design.HideUtilityClassConstructorCheck" />
+		<module name="io.spring.javaformat.checkstyle.check.SpringHideUtilityClassConstructor" />
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.MutableExceptionCheck" />
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.InnerTypeLastCheck" />
 		<module name="com.puppycrawl.tools.checkstyle.checks.design.OneTopLevelClassCheck" />

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/check/HideUtilityClassConstructorInvalid.txt

@@ -0,0 +1 @@
++HideUtilityClassConstructorInvalid.java:22:1: hide.utility.class [SpringHideUtilityClassConstructor]

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/check/HideUtilityClassConstructorSpringApplication.txt

@@ -0,0 +1 @@
++0 errors

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/check/HideUtilityClassConstructorSpringConfiguration.txt

@@ -0,0 +1 @@
++0 errors

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/source/HideUtilityClassConstructorInvalid.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Invlid utility class.
+ *
+ * @author Phillip Webb
+ */
+public class HideUtilityClassConstructorInvalid {
+
+	public static void main(String[] args) {
+	}
+
+}

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/source/HideUtilityClassConstructorSpringApplication.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Usually invalid utility class but OK because it's a Spring Application.
+ *
+ * @author Phillip Webb
+ */
+@SpringBootApplication
+public class HideUtilityClassConstructorSpringApplication {
+
+	public static void main(String[] args) {
+	}
+
+}

spring-javaformat/spring-javaformat-checkstyle/src/test/resources/source/HideUtilityClassConstructorSpringConfiguration.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Usually invalid utility class but OK because it's a Spring Configuration.
+ *
+ * @author Phillip Webb
+ */
+@Configuration
+public class HideUtilityClassConstructorSpringConfiguration {
+
+	@Bean
+	public static String myBean() {
+		return "foo";
+	}
+
+}