@Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("primary key(");
    for (PrimaryKeyField field : pkFields) {
      sb.append(field).append(",");
    }
    if (!pkFields.isEmpty()) {
      sb.deleteCharAt(sb.length() - 1);
    }
    sb.append(")");
    return sb.toString();
  }
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