Mojo: validate nullability in Java serialization.

mojo/public/tools/bindings/generators/mojom_java_generator.py

Index: mojo/public/tools/bindings/generators/mojom_java_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_java_generator.py b/mojo/public/tools/bindings/generators/mojom_java_generator.py
index 91e8b8e0a578702157417f1d12783112ac468802..3cf5d0fd7dcae9c9492e1ae9f095afc124248382 100644
--- a/mojo/public/tools/bindings/generators/mojom_java_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_java_generator.py
@@ -203,6 +203,11 @@ def EncodeMethod(context, kind, variable, offset, bit):
   params = [ variable, str(offset) ]
   if (kind == mojom.BOOL):
     params.append(str(bit))
+  if mojom.IsReferenceKind(kind):
+    if mojom.IsAnyArrayKind(kind):
+      params.append(GetArrayNullabilityFlags(kind))
+    else:
+      params.append(GetJavaTrueFalse(mojom.IsNullableKind(kind)))
   if mojom.IsAnyArrayKind(kind):
     if mojom.IsFixedArrayKind(kind):
       params.append(str(kind.length))