presto-main/src/main/java/io/prestosql/metadata/FunctionId.java/FunctionId/equals
class FunctionId:    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        FunctionId that = (FunctionId) o;
        return id.equals(that.id);
    }