@Override
    public int getFieldNumber(String name)
    {
        return name.length() == 1 && name.charAt(0) == '_' ? ID_POJO : 0;
    }
This schema delegates to another schema derived from the input.

@author David Yu
@created Jan 21, 2011
protostuff-runtime/src/main/java/io/protostuff/runtime/DerivativeSchema.java