Fix javadoc - lombok builder incompatibility

Author: oliemansm

graphql-webclient/src/main/java/graphql/kickstart/spring/webclient/boot/GraphQLRequestBody.java

@@ -11,4 +11,12 @@ class GraphQLRequestBody {
   Object variables;
   String operationName;
 
+  static GraphQLRequestBodyBuilder builder() {
+    return new GraphQLRequestBodyBuilder();
+  }
+
+  static class GraphQLRequestBodyBuilder {
+    // added this partial builder to let Javadoc play nice with Lombok, see https://stackoverflow.com/a/58809436/12507062
+  }
+
 }