final String uniqueId
    }

    MutableUnitOfWork build() {
        Map<String, OutputPropertySpec> outputFileSpecs = Maps.transformEntries(outputFiles, { key, value -> outputFileSpec(value) })
        Map<String, OutputPropertySpec> outputDirSpecs = Maps.transformEntries(outputDirs, { key, value -> outputDirectorySpec(value) })
        Map<String, OutputPropertySpec> outputs = outputFileSpecs + outputDirSpecs