mojo: Fix Java binding generator for array<enum>

Values should be validated by iterating with i{{level+1}}.

This is a cherry-pick of http://crrev.com/c/2532547

Bug: 173033003
Test: build
Change-Id: I896799dd408000c4f391e66dfeba92f0378a0f4e
diff --git a/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl b/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
index 7af57bd..568db8e 100644
--- a/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
@@ -100,8 +100,8 @@
 {%-     else %}
 {
 {%-     endif %}
-    for (int i{{level}} = 0; i{{level}} < {{variable}}.length; ++i{{level}}) {
-        {{kind.kind|java_class_for_enum}}.validate({{variable}}[i{{level}}]);
+    for (int i{{level+1}} = 0; i{{level+1}} < {{variable}}.length; ++i{{level+1}}) {
+        {{kind.kind|java_class_for_enum}}.validate({{variable}}[i{{level+1}}]);
     }
 }
 {%-   elif kind|is_enum_kind %}