code: private static List<String> getIncompatibleNames(Schema schema) {
      NameValidation validation = new NameValidation();
      SchemaUtil.visit(schema, validation);
      return validation.getIncompatibleNames();
    }
docs: Returns a list of field names from the schema that contain characters that
  are known to be incompatible with some projects, such as Hive or HBase.
  
  @param schema a {@link org.apache.avro.Schema} to check
  @return a {@link java.util.List} of incompatible field names