Enable Animal Sniffer checking of spring-boot-loader-tools

Previously, Animal Sniffer checking of spring-boot-loader-tools
was disabled as it failed with an NPE. This has been fixed in
Animal Sniffer 1.15.

This commit upgrades Animal Sniffer to 1.15 and adds the necessary
annotations to suppress failures for safe usage of sun.* and Java 7
APIs.

Note that UsesUnsafeJava has been copied from spring-boot and made
package-private. This retains the clearer intent of the custom
annotation (versus @IgnoreJRERequirement) while avoiding the change
in the build order that would be necessary for
spring-boot-loader-tools to use the annotation from spring-boot.

Closes spring-projectsgh-5284

spring-boot-parent/pom.xml

@@ -289,7 +289,7 @@
 				<plugin>
 					<groupId>org.codehaus.mojo</groupId>
 					<artifactId>animal-sniffer-maven-plugin</artifactId>
-					<version>1.14</version>
+					<version>1.15</version>
 				</plugin>
 				<plugin>
 					<groupId>org.codehaus.cargo</groupId>

spring-boot-tools/spring-boot-loader-tools/pom.xml

@@ -132,8 +132,10 @@
 				<groupId>org.codehaus.mojo</groupId>
 				<artifactId>animal-sniffer-maven-plugin</artifactId>
 				<configuration>
-					<!-- The use of SignalUtils seems to mess up animal sniffer -->
-					<skip>true</skip>
+					<annotations>
+						<annotation>org.springframework.boot.loader.tools.UsesUnsafeJava</annotation>
+						<annotation>org.springframework.lang.UsesJava7</annotation>
+					</annotations>
 				</configuration>
 			</plugin>
 		</plugins>

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/JarWriter.java

@@ -42,6 +42,8 @@
 import java.util.zip.CRC32;
 import java.util.zip.ZipEntry;
 
+import org.springframework.lang.UsesJava7;
+
 /**
  * Writes JAR content, ensuring valid directory entries are always create and duplicate
  * items are ignored.
@@ -86,6 +88,7 @@ public JarWriter(File file, LaunchScript launchScript)
 		this.jarOutput = new JarOutputStream(fileOutputStream);
 	}
 
+	@UsesJava7
 	private void setExecutableFilePermission(File file) {
 		try {
 			Path path = file.toPath();

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/SignalUtils.java

@@ -26,6 +26,7 @@
  * @since 1.1.0
  */
 @SuppressWarnings("restriction")
+@UsesUnsafeJava
 public final class SignalUtils {
 
 	private static final Signal SIG_INT = new Signal("INT");

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/UsesUnsafeJava.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2015 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 org.springframework.boot.loader.tools;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Indicates that the annotated element uses unsafe Java calls.
+ *
+ * @author Phillip Webb
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target({ ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE })
+@Documented
+@interface UsesUnsafeJava {
+}