@@ -27,6 +27,7 @@
  * You can set this up via {@link ExecutionInput.Builder#context(graphql.GraphQLContext.Builder)}
  */
 @PublicApi
+@ThreadSafe
 @SuppressWarnings("unchecked")
 public class GraphQLContext {
 
 
@@ -0,0 +1,19 @@
+package graphql;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.CONSTRUCTOR;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.TYPE;
+
+/**
+ * This represents code that is known to be mutable but thread safe.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(value = {CONSTRUCTOR, METHOD, TYPE})
+@Documented
+public @interface ThreadSafe {
+}