public Types.StructType primaryKeyStruct() {
    return Types.StructType.of(
        pkFields.stream()
            .map(field -> schema.findField(field.fieldName()))
            .collect(Collectors.toList()));
  }
parse primary key spec from table properties

@param schema - base store table schema
@param keyDescription - key description of {#{@link #description}}
@return primary key spec.
amoro-format-iceberg/src/main/java/org/apache/amoro/table/PrimaryKeySpec.java