// use original key
        return parent.compute(key, remappingFunction);
    }

    @Override
    public V merge(final K key, final V value, final BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
        // use original key
        return parent.merge(key, value, remappingFunction);
    }

	}
	if len(summary.tiers) != 0 {
		if e.AllTierStats == nil {
			e.AllTierStats = newAllTierStats()
		}
		e.AllTierStats.addSizes(summary.tiers)
	}
}

// merge other data usage entry into this, excluding children.
func (e *dataUsageEntry) merge(other dataUsageEntry) {
	e.Objects += other.Objects
	e.Versions += other.Versions
	e.DeleteMarkers += other.DeleteMarkers
	e.Size += other.Size

  TFE_OpSetAttrInt(op.get(), "group_size", group_size);
  TFE_OpSetAttrInt(op.get(), "group_key", 0);
  TFE_OpSetAttrInt(op.get(), "instance_key", 0);
  const std::string merge_op("Add");
  TFE_OpSetAttrString(op.get(), "merge_op", merge_op.c_str(),
                      merge_op.length());
  const std::string final_op("Id");
  TFE_OpSetAttrString(op.get(), "final_op", final_op.c_str(),
                      final_op.length());

        _ * classDoc.classExtensions >> []
        _ * classDoc.subClasses >> []

        when:
        def result = parse('<chapter/>', document)
        withCategories {
            renderer.merge(classDoc, result)
        }

        then:
        formatTree(result) == '''<chapter>
    <section>
        <title>Properties</title>
        <table>
            <title>Properties - Class</title>

of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions: