This is preferred:

```groovy
public interface NewThing {
    Property<String> getSomeProperty()
}
```

This is acceptable:

```groovy
public interface NewThing {
    Property<String> getSomeProperty()
}

abstract class DefaultNewThing implements NewThing {

 *
 * <p>Popular escapers are defined as constants in classes like {@link
 * com.google.common.html.HtmlEscapers} and {@link com.google.common.xml.XmlEscapers}. To create
 * your own escapers extend this class and implement the {@link #escape(char)} method.
 *
 * @author Sven Mawson
 * @since 15.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class CharEscaper extends Escaper {

      int i = 0;
      for (Object e : elements) {
        array[i++] = (Float) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of
     * {@link #create(Object...)}.
     */
    protected abstract List<Float> create(Float[] elements);

    @Override
    public Float[] createArray(int length) {

      int i = 0;
      for (Object e : elements) {
        array[i++] = (Float) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of
     * {@link #create(Object...)}.
     */
    protected abstract List<Float> create(Float[] elements);

    @Override
    public Float[] createArray(int length) {

      int i = 0;
      for (Object e : elements) {
        array[i++] = (Integer) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of
     * {@link #create(Object...)}.
     */
    protected abstract List<Integer> create(Integer[] elements);

    @Override
    public Integer[] createArray(int length) {

  // mycompany.com/my-custom-protocol.
  // +optional
  optional string appProtocol = 4;
}

// EndpointSlice represents a subset of the endpoints that implement a service.
// For a given service there may be multiple EndpointSlice objects, selected by
// labels, which must be joined to produce the full set of endpoints.
message EndpointSlice {
  // Standard object's metadata.

import java.time.Duration;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Base class for services that can implement {@link #startUp}, {@link #run} and {@link #shutDown}
 * methods. This class uses a single thread to execute the service; consider {@link AbstractService}
 * if you would like to manage any threading manually.
 *

  repeated string audiences = 4;

  // Error indicates that the token couldn't be checked
  // +optional
  optional string error = 3;
}

// UserInfo holds the information about the user needed to implement the
// user.Info interface.
message UserInfo {
  // The name that uniquely identifies this user among all active users.
  // +optional
  optional string username = 1;

import static com.google.common.math.MathPreconditions.checkRoundingUnnecessary;

import com.google.common.annotations.GwtIncompatible;
import java.math.RoundingMode;

/**
 * Helper type to implement rounding {@code X} to a representable {@code double} value according to
 * a {@link RoundingMode}.
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class ToDoubleRounder<X extends Number & Comparable<X>> {

#### Caching