@Override
		public boolean equals(Object obj) {
			if (!(obj instanceof PrecedencePredicate)) {
				return false;
			}

			if (this == obj) {
				return true;
			}

			PrecedencePredicate other = (PrecedencePredicate)obj;
			return this.precedence == other.precedence;
		}
The default {@link SemanticContext}, which is semantically equivalent to
a predicate of the form {@code {true}?}.
runtime/Java/src/org/antlr/v4/runtime/atn/SemanticContext.java