code: public void putField(final JBBPNumericField field) {
      JBBPUtils.assertNotNull(field, "Field must not be null");
      final JBBPNamedFieldInfo fieldName = field.getNameInfo();
      JBBPUtils.assertNotNull(fieldName, "Field name info must not be null");
      this.fieldMap.put(fieldName, field);
    }
docs: Put a numeric field into map.
  
  @param field a field to be added into map or replace already exists one, it
  must not be null
  @throws NullPointerException if the field is null or if it is an anonymous
  field