Copying required field to union type vector (#4407)

* Eclipse ignore

* TypeScript support

* Prefixing enums

* Test results

* Merged JS and TS generators

* Fixed AppVeyor build problems

* Fixed more AppVeyor build problems

* Fixed more AppVeyor build problems

* Changed TS flag to options struct

* Storing options by value

* Removed unneeded const

* Re-export support for unions

* Uint support

* Casting bools to numbers for mutation

* TS shell tests

* Reverted generates js test file to original version

* Backing up js tests and properly generating test data

* Not importing flatbuffers for TS test generation

* Not overwriting generated js for tests

* AppVeyor test fixes

* Generating the most strict TS code possible

* Not returning null when creating vectors

* Not returning null from struct contructors

* Copying required field to union type vector

* Removed unneccessary bool

src/idl_parser.cpp

@@ -745,6 +745,10 @@ CheckedError Parser::ParseField(StructDef &struct_def) {
   }
 
   if (typefield) {
+    if (!IsScalar(typefield->value.type.base_type)) {
+      // this is a union vector field
+      typefield->required = field->required;
+    }
     // If this field is a union, and it has a manually assigned id,
     // the automatically added type field should have an id as well (of N - 1).
     auto attr = field->attributes.Lookup("id");