presto-main/src/main/java/io/prestosql/sql/analyzer/FieldId.java/FieldId/equals
class FieldId:    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        FieldId fieldId = (FieldId) o;
        return fieldIndex == fieldId.fieldIndex &&
                Objects.equals(relationId, fieldId.relationId);
    }