Add Java 9 jspecify annotations including module level ones

third-party/java9-annotations/module-info.java

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+module java9_annotations {
+    exports org.jspecify.nullness;
+    // add packages needed to export
+}

third-party/java9-annotations/org/jspecify/nullness/NullMarked.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2018-2020 The JSpecify 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.jspecify.nullness;
+
+import static java.lang.annotation.ElementType.MODULE;
+import static java.lang.annotation.ElementType.PACKAGE;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * <b>WARNING:</b> This is not the final class name or package name for this annotation. In
+ * addition, we are still discussing questions about semantics, particularly around type-variable
+ * usages. After that, changes and documentation will follow.
+ *
+ * <p>These annotations exist only as a skeleton for the final product. At this point, we are not
+ * even building prototypes that use them.
+ */
+@Documented
+@Target({TYPE, PACKAGE, MODULE})
+@Retention(RUNTIME)
+public @interface NullMarked {}

third-party/java9-annotations/org/jspecify/nullness/Nullable.java

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+/*
+ * Copyright 2018-2020 The JSpecify 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.jspecify.nullness;
+
+import static java.lang.annotation.ElementType.TYPE_USE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * <b>WARNING:</b> This is not the final package name for this annotation. In addition, we are still
+ * discussing questions about semantics, particularly around type-variable usages. After that,
+ * changes and documentation will follow.
+ *
+ * <p>These annotations exist only as a skeleton for the final product. At this point, we are not
+ * even building prototypes that use them.
+ */
+@Documented
+@Target(TYPE_USE)
+@Retention(RUNTIME)
+public @interface Nullable {}

third-party/java9-annotations/org/jspecify/nullness/NullnessUnspecified.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2018-2020 The JSpecify 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.jspecify.nullness;
+
+import static java.lang.annotation.ElementType.TYPE_USE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * <b>WARNING:</b> This is not the final class name or package name for this annotation. We are not
+ * even sure if an annotation like this one will make the 1.0 release.
+ *
+ * <p>These annotations exist only as a skeleton for the final product. At this point, we are not
+ * even building prototypes that use them.
+ */
+@Documented
+@Target(TYPE_USE)
+@Retention(RUNTIME)
+public @interface NullnessUnspecified {}