Partially revert 59d911d6

This commit restores the public `UsesUnsafeJava` and flag it as
deprecated.

Closes gh-14072

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

+/*
+ * Copyright 2012-2017 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
+ * @deprecated as of 2.0.5
+ */
+@Retention(RetentionPolicy.CLASS)
+@Target({ ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE })
+@Documented
+@Deprecated
+public @interface UsesUnsafeJava {
+
+}

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

+/*
+ * Copyright 2012-2017 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.
+ */
+
+/**
+ * Language feature annotations.
+ */
+package org.springframework.boot.lang;