Add @UsesUnsafeJava annotation

Add a new annotation to indicate to Animal Sniffer that a method uses
a call to `Unsafe`.

Closes gh-3080

spring-boot-parent/pom.xml

@@ -513,6 +513,7 @@
 					<annotations>
 						<annotation>org.springframework.lang.UsesJava8</annotation>
 						<annotation>org.springframework.lang.UsesJava7</annotation>
+						<annotation>org.springframework.boot.lang.UsesUnsafeJava</annotation>
 					</annotations>
 				</configuration>
 				<executions>

spring-boot/src/main/java/org/springframework/boot/lang/UsesUnsafeJava.java

@@ -0,0 +1,35 @@
+/*
+ * 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.lang;
+
+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
+ * @since 1.3.0
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target({ ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE })
+@Documented
+public @interface UsesUnsafeJava {
+}

spring-boot/src/main/java/org/springframework/boot/lang/package-info.java

@@ -0,0 +1,19 @@
+/*
+ * 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.
+ */
+/**
+ * @author pwebb
+ */
+package org.springframework.boot.lang;