[BEAM-3640] Part1: Update Checkstyle to enforce blank lines for impor…

…ts and classdefs

examples/java/src/main/java/org/apache/beam/examples/complete/game/utils/WriteToBigQuery.java

@@ -91,6 +91,7 @@ FieldFn<InputT> getFieldFn() {
  return this.fieldFn;
  }
  }
+
  /** Convert each key/score pair into a BigQuery TableRow as specified by fieldFn. */
  protected class BuildRowFn extends DoFn<InputT, TableRow> {
 

runners/core-construction-java/src/main/java/org/apache/beam/runners/core/construction/WriteFilesTranslation.java

@@ -294,6 +294,7 @@ public FunctionSpec translate(
  return new RawWriteFiles(protoTransform, rehydratedComponents);
  }
  }
+
  /** Registers {@link WriteFilesTranslator}. */
  @AutoService(TransformPayloadTranslatorRegistrar.class)
  public static class Registrar implements TransformPayloadTranslatorRegistrar {

runners/core-construction-java/src/test/java/org/apache/beam/runners/core/construction/CombineTranslationTest.java

@@ -220,5 +220,5 @@ public boolean equals(Object other) {
  public int hashCode() {
  return TestCombineFnWithContext.class.hashCode();
  }
- };
+ }
 }

runners/core-construction-java/src/test/java/org/apache/beam/runners/core/construction/PTransformMatchersTest.java

@@ -132,6 +132,7 @@ public PCollection<Integer> expand(PCollection<KV<String, Integer>> input) {
  input.getPipeline(), input.getWindowingStrategy(), input.isBounded(), VarIntCoder.of());
  }
  }
+
  PTransformMatcher matcher = PTransformMatchers.classEqualTo(MyPTransform.class);
  MyPTransform subclass = new MyPTransform() {};
 
@@ -160,7 +161,9 @@ public void simpleProcess(ProcessContext ctxt) {
  ctxt.output(ctxt.element().getValue() + 1);
  }
  };
+
  private abstract static class SomeTracker extends RestrictionTracker<Void, Void> {}
+
  private DoFn<KV<String, Integer>, Integer> splittableDoFn =
  new DoFn<KV<String, Integer>, Integer>() {
  @ProcessElement

runners/core-java/src/test/java/org/apache/beam/runners/core/StatefulDoFnRunnerTest.java

@@ -235,5 +235,5 @@ public void processElement(
  Integer currentValue = MoreObjects.firstNonNull(state.read(), 0);
  state.write(currentValue + 1);
  }
- };
+ }
 }

runners/direct-java/src/test/java/org/apache/beam/runners/direct/CloningBundleFactoryTest.java

@@ -173,6 +173,7 @@ public void keyedBundleDecodeFailsAddFails() {
  }
 
  static class Record {}
+
  static class RecordNoEncodeCoder extends AtomicCoder<Record> {
 
  @Override

runners/google-cloud-dataflow-java/src/main/java/org/apache/beam/runners/dataflow/BatchStatefulParDoOverrides.java

@@ -120,6 +120,7 @@ public Map<PValue, ReplacementOutput> mapOutputs(
  return ReplacementOutputs.singleton(outputs, newOutput);
  }
  }
+
  private static class MultiOutputOverrideFactory<K, InputT, OutputT>
  implements PTransformOverrideFactory<
  PCollection<KV<K, InputT>>, PCollectionTuple, ParDo.MultiOutput<KV<K, InputT>, OutputT>> {

runners/google-cloud-dataflow-java/src/main/java/org/apache/beam/runners/dataflow/DataflowRunner.java

@@ -876,6 +876,7 @@ public void visitValue(PValue value, Node producer) {
  }
  }
  }
+
  BoundednessVisitor visitor = new BoundednessVisitor();
  p.traverseTopologically(visitor);
  return visitor.boundedness == IsBounded.UNBOUNDED;
@@ -1540,6 +1541,7 @@ public void process(ProcessContext c) throws Exception {
  .setCoder(source.getOutputCoder());
  }
  }
+
  /**
  * A marker {@link DoFn} for writing the contents of a {@link PCollection} to a streaming
  * {@link PCollectionView} backend implementation.

runners/java-fn-execution/src/test/java/org/apache/beam/runners/fnexecution/control/FnApiControlClientTest.java

@@ -136,6 +136,7 @@ public void testOnErrorCancelsOutstanding() throws Exception {
  client.handle(BeamFnApi.InstructionRequest.newBuilder().setInstructionId(id).build());
 
  class FrazzleException extends Exception {}
+
  client.asResponseObserver().onError(new FrazzleException());
 
  thrown.expect(ExecutionException.class);

sdks/java/build-tools/src/main/resources/beam/checkstyle.xml

@@ -379,6 +379,14 @@ page at http:https://checkstyle.sourceforge.net/config.html -->
  WHITESPACE CHECKS
 
  -->
+ <module name="EmptyLineSeparator">
+ <property name="allowNoEmptyLineBetweenFields" value="false"/>
+ <property name="allowMultipleEmptyLines" value="true"/>
+ <property name="allowMultipleEmptyLinesInsideClassMembers" value="true"/>
+ <property name="tokens" value="IMPORT,CLASS_DEF" />
+ <!-- eventually start adding: ,INTERFACE_DEF,ENUM_DEF,
+ STATIC_INIT,INSTANCE_INIT,METHOD_DEF,CTOR_DEF, VARIABLE_DEF -->
+ </module>
 
  <module name="WhitespaceAround">
  <!-- Checks that various tokens are surrounded by whitespace.

sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/reflect/DoFnSignature.java

@@ -366,6 +366,7 @@ public abstract static class ProcessContextParameter extends Parameter {
  public abstract static class OnTimerContextParameter extends Parameter {
  OnTimerContextParameter() {}
  }
+
  /**
  * Descriptor for a {@link Parameter} of type {@link BoundedWindow}.
  *

sdks/java/core/src/test/java/org/apache/beam/sdk/PipelineTest.java

@@ -436,12 +436,14 @@ public PCollection<Integer> expand(PCollection<Integer> input) {
  return input.apply("custom_name", Sum.integersGlobally());
  }
  }
+
  class ReplacementTransform extends PTransform<PCollection<Integer>, PCollection<Integer>> {
  @Override
  public PCollection<Integer> expand(PCollection<Integer> input) {
  return input.apply("custom_name", Max.integersGlobally());
  }
  }
+
  class ReplacementOverrideFactory
  implements PTransformOverrideFactory<
  PCollection<Integer>, PCollection<Integer>, OriginalTransform> {

sdks/java/core/src/test/java/org/apache/beam/sdk/coders/AvroCoderTest.java

@@ -442,6 +442,7 @@ private static class NonDeterministicArray {
  @SuppressWarnings("unused")
  private UnorderedMapClass[] arrayField;
  }
+
  @Test
  public void testDeterministicNonDeterministicArray() {
  assertNonDeterministic(AvroCoder.of(NonDeterministicArray.class),
@@ -714,7 +715,9 @@ private abstract static class DeterministicUnionBase {}
 
  @Union({ UnionCase1.class, UnionCase2.class, UnionCase3.class })
  private abstract static class NonDeterministicUnionBase {}
+
  private static class UnionCase1 extends DeterministicUnionBase {}
+
  private static class UnionCase2 extends DeterministicUnionBase {
  @SuppressWarnings("unused")
  String field;
@@ -903,6 +906,7 @@ private static class SomeGeneric<T> {
  @SuppressWarnings("unused")
  private T foo;
  }
+
  private static class Foo {
  @SuppressWarnings("unused")
  String id;

sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/ParDoTest.java

@@ -144,6 +144,7 @@ public void processElement(ProcessContext c, BoundedWindow window) {
  + ":" + window.maxTimestamp().getMillis());
  }
  }
+
  static class TestNoOutputDoFn extends DoFn<Integer, String> {
  @ProcessElement
  public void processElement(DoFn<Integer, String>.ProcessContext c) throws Exception {}

sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/reflect/DoFnInvokersTest.java

@@ -120,6 +120,7 @@ class MockFn extends DoFn<String, String> {
  @ProcessElement
  public void processElement(ProcessContext c) throws Exception {}
  }
+
  MockFn mockFn = mock(MockFn.class);
  assertEquals(stop(), invokeProcessElement(mockFn));
  verify(mockFn).processElement(mockProcessContext);
@@ -180,6 +181,7 @@ class MockFn extends DoFn<String, String> {
  @DoFn.ProcessElement
  public void processElement(ProcessContext c, IntervalWindow w) throws Exception {}
  }
+
  MockFn fn = mock(MockFn.class);
  assertEquals(stop(), invokeProcessElement(fn));
  verify(fn).processElement(mockProcessContext, mockWindow);
@@ -204,6 +206,7 @@ class MockFn extends DoFn<String, String> {
  public void processElement(ProcessContext c, @StateId(stateId) ValueState<Integer> valueState)
  throws Exception {}
  }
+
  MockFn fn = mock(MockFn.class);
  assertEquals(stop(), invokeProcessElement(fn));
  verify(fn).processElement(mockProcessContext, mockState);
@@ -230,6 +233,7 @@ public void processElement(ProcessContext c, @TimerId(timerId) Timer timer)
  @OnTimer(timerId)
  public void onTimer() {}
  }
+
  MockFn fn = mock(MockFn.class);
  assertEquals(stop(), invokeProcessElement(fn));
  verify(fn).processElement(mockProcessContext, mockTimer);
@@ -254,6 +258,7 @@ public SomeRestrictionTracker newTracker(SomeRestriction restriction) {
  return null;
  }
  }
+
  MockFn fn = mock(MockFn.class);
  when(fn.processElement(mockProcessContext, null)).thenReturn(resume());
  assertEquals(resume(), invokeProcessElement(fn));
@@ -277,6 +282,7 @@ public void before() {}
  @Teardown
  public void after() {}
  }
+
  MockFn fn = mock(MockFn.class);
  DoFnInvoker<String, String> invoker = DoFnInvokers.invokerFor(fn);
  invoker.invokeSetup();
@@ -446,6 +452,7 @@ public RestrictionWithDefaultTracker getInitialRestriction(String element) {
  return null;
  }
  }
+
  MockFn fn = mock(MockFn.class);
  DoFnInvoker<String, String> invoker = DoFnInvokers.invokerFor(fn);
 
@@ -760,7 +767,7 @@ public void onMyTimer(IntervalWindow w) {
  static class StableNameTestDoFn extends DoFn<Void, Void> {
  @ProcessElement
  public void process() {}
- };
+ }
 
  /**
  * This is a change-detector test that the generated name is stable across runs.

sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/reflect/DoFnSignaturesSplittableDoFnTest.java

@@ -199,6 +199,7 @@ class UnsplittableFn extends DoFn<Integer, String> {
  @ProcessElement
  public void process(ProcessContext context) {}
  }
+
  assertEquals(
  PCollection.IsBounded.BOUNDED,
  DoFnSignatures

sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/reflect/OnTimerInvokersTest.java

@@ -117,7 +117,7 @@ public void process() {}
 
  @OnTimer(TIMER_ID)
  public void onMyTimer() {}
- };
+ }
 
  /**
  * This is a change-detector test that the generated name is stable across runs.

sdks/java/core/src/test/java/org/apache/beam/sdk/transforms/windowing/WindowingTest.java

@@ -68,6 +68,7 @@ public void processElement(ProcessContext c, BoundedWindow window) {
  + ":" + window);
  }
  }
+
  private WindowFn<? super String, ?> windowFn;
  public WindowedCount(WindowFn<? super String, ?> windowFn) {
  this.windowFn = windowFn;

sdks/java/io/elasticsearch/src/main/java/org/apache/beam/sdk/io/elasticsearch/ElasticsearchIO.java

@@ -858,6 +858,7 @@ public void closeClient() throws Exception {
  }
  }
  }
+
  static int getBackendVersion(ConnectionConfiguration connectionConfiguration) {
  try (RestClient restClient = connectionConfiguration.createClient()) {
  Response response = restClient.performRequest("GET", "");