@Override
	public boolean equals(Object a, Object b) {
		if (a == null) {
			return b == null;
		}

		return a.equals(b);
	}
{@inheritDoc}

<p>This implementation relies on object equality. If both objects are
{@code null}, this method returns {@code true}. Otherwise if only
{@code a} is {@code null}, this method returns {@code false}. Otherwise,
this method returns the result of
{@code a.}{@link Object#equals equals}{@code (b)}.</p>
runtime/Java/src/org/antlr/v4/runtime/misc/ObjectEqualityComparator.java