Generate java bindings for constants.

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

+{%  macro set_default(variable, module, kind, value, depth=0) %}
+{%    if kind|is_string_kind %}
+{{variable}} = {{value|expression_to_text(module)}};
+{%    elif kind|is_array_kind %}
+{%     set _ = value|verify_token_type("ARRAY") %}
+{{variable}} = {{kind|new_array(value[1]|length)}};
+{%     for element in value[1] -%}
+{{set_default(variable~'['~loop.index0~']', module, kind.kind, element, depth+1)}}
+{%-    endfor %}
+{%    elif kind|is_object_kind %}
+{%      set _ = value|verify_token_type("OBJECT") %}
+{{kind|java_type}}.Builder tmp{{depth}} = {{kind|java_type}}.newBuilder();
+{%    for element in value[1] %}
+{%      set subfield = kind.fields[loop.index0] %}
+{
+    {{subfield.kind|java_type}} tmp{{depth+1}};
+    {{set_default('tmp'~(depth+1), module, subfield.kind, element, depth+2)|indent(4)}}
+    tmp{{depth}}.set{{subfield.name|camelcase|capitalize_first}}(tmp{{depth+1}});
+}
+{%    endfor %}
+{{variable}} = tmp{{depth}}.build();
+{%    else %}
+{{variable}} = ({{kind|java_type}}) {{value|expression_to_text(module)}};
+{%    endif %}
+{%  endmacro %}