public static final String fieldName(int number)
    {
        switch (number)
        {
            case 1: return FIELD_NAME_VALUE;
            case 2: return FIELD_NAME_NULL;
            default: return null;
        }
    }
A schema for standard jdk {@link Collection collections}. Null values are not serialized/written.
<p>
If {@link #preserveNull} is false and your application relies on {@link Object#equals(Object)}, 
it will fail when a serialized collection contains null values.

@author David Yu
@created Jan 26, 2011
protostuff-collectionschema/src/main/java/io/protostuff/CollectionSchema.java