VariableLengthByteArraySortedSet extends AbstractByteArraySortedSet { @Override public String toString() { return "VariableLengthByteArraySortedSet{" + "elementsCount=" + elements.size() + '}'; } VariableLengthByteArraySortedSet(
            @NotNull
            final SortedSet<UnsignedByteArray> elements); @Override long getSizeInBytes(); @Override void writeTo(
            @NotNull
            final OutputStream os); @Override String toString();  }
@Test public void string() { final SortedSet<UnsignedByteArray> elements = new TreeSet<>(); final int size = 10; for (long i = 0; i < size; i++) elements.add(from(i)); final ByteArraySortedSet set = new VariableLengthByteArraySortedSet( elements); final String s = set.toString(); assertTrue(s.contains(Integer.toString(size))); }