Generate java bindings for constants.

mojo/public/tools/bindings/generators/java_templates/java_macros.tmpl

+{%  macro build_default(module, kind, value) %}
+{%    if kind|is_string_kind %}
+{{value|expression_to_text(module)}}
+{%    elif kind|is_array_kind %}
+{%     set _ = value|verify_token_type("ARRAY") %}
+new {{kind.kind|java_type}}[] {
+{%     for element in value[1] %}
+    {{build_default(module, kind.kind, element)|indent(4)}}{%- if not loop.last %}, {% endif %}
+
+{%    endfor %}
+}
+{%    elif kind|is_object_kind %}
+{%      set _ = value|verify_token_type("OBJECT") %}
+ {{kind|java_type}}.newBuilder()
+{%    for element in value[1] %}
+{%      set subfield = kind.fields[loop.index0] %}
+    .set{{subfield.name|camelcase|capitalize_first}}({{build_default(module, subfield.kind, element)|indent(8)}})
+{%    endfor %}
+    .build()
+{%    else %}
+({{kind|java_type}}) {{value|expression_to_text(module)}}
+{%    endif %}
+{%  endmacro %}