return context.getInputChanges();
            }

            @Override
            public Optional<ImmutableSortedMap<String, FileSystemSnapshot>> getPreviouslyProducedOutputs() {
                return context.getPreviousExecutionState()
                    .map(PreviousExecutionState::getOutputFilesProducedByWork);
            }
        };
        UnitOfWork.WorkOutput workOutput;

         * {@link Optional#empty()} is information about a previous execution is not available.
         */
        Optional<ImmutableSortedMap<String, FileSystemSnapshot>> getPreviouslyProducedOutputs();
    }

    /**
     * The result of executing the user code.
     */
    interface WorkOutput {
        /**

        return task::getPath;
    }

    @Override
    public WorkOutput execute(ExecutionRequest executionRequest) {
        FileCollection previousFiles = executionRequest.getPreviouslyProducedOutputs()
            .<FileCollection>map(previousOutputs -> new PreviousOutputFileCollection(task, taskDependencyFactory, fileCollectionFactory, previousOutputs))
            .orElseGet(FileCollectionFactory::empty);