public Field fieldFrom(Schema schema) {
        if (schema == null) return null;

        Schema current = schema;
        for (String pathSegment : stepsWithoutLast()) {
            final Field field = current.field(pathSegment);
            if (field != null) {
                current = field.schema();
            } else {
                return null;
            }
        }
        return current.field(lastStep());
    }
Access a {@code Field} at the current path within a schema {@code Schema}
If field is not found, then {@code null} is returned.
connect/transforms/src/main/java/org/apache/kafka/connect/transforms/field/SingleFieldPath.java