@Override
  public boolean shouldConvertRaggedUnionTypesToVarying() {
    // when union a number of CHAR types of different lengths, we should cast to a VARCHAR
    // this fixes the problem of CASE WHEN with different length string literals but get wrong
    // result with additional space suffix
    return true;
  }
Custom type system for Flink.

<p>Copied from flink-1.18.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/planner/calcite/FlinkTypeSystem.java