android/guava/src/com/google/common/collect/TreeBasedTable.java
public static <R extends Comparable, C extends Comparable, V> TreeBasedTable<R, C, V> create() {
    return new TreeBasedTable<>(Ordering.natural(), Ordering.natural());
  }
public static <R extends Comparable, C extends Comparable, V> TreeBasedTable<R, C, V> create() {
    return new TreeBasedTable<>(Ordering.natural(), Ordering.natural());
  }
Creates an empty {@code TreeBasedTable} that uses the natural orderings of both row and column
keys.

<p>The method signature specifies {@code R extends Comparable} with a raw {@link Comparable},
instead of {@code R extends Comparable<? super R>}, and the same for {@code C}. That's
necessary to support classes defined without generics.