@Override
    public String toString() {
        return "TransformationStage{" +
                "predicate=" + predicate +
                ", transformation=" + transformation +
                ", negate=" + negate +
                '}';
    }
Wrapper for a {@link Transformation} and corresponding optional {@link Predicate}
which applies the transformation when the {@link Predicate} is true (or false, according to {@code negate}).
If no {@link Predicate} is provided, the transformation will be unconditionally applied.
@param <R> The type of record (must be an implementation of {@link ConnectRecord})
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/TransformationStage.java