@TableModel
  public void toLowerCase() {
    devicePath.toLowerCase();
    if (measurements == null) {
      return;
    }
    for (int i = 0; i < measurements.length; i++) {
      if (measurements[i] != null) {
        measurements[i] = measurements[i].toLowerCase();
      }
    }
    if (measurementSchemas != null) {
      for (final MeasurementSchema measurementSchema : measurementSchemas) {
        if (measurementSchema != null) {
          measurementSchema.setMeasurementName(
              measurementSchema.getMeasurementName().toLowerCase());
        }
      }
    }
  }
This function is used in splitting. Traverse two lists: logicalViewSchemaList, measurements,
then find out all devices in this statement. Those devices will map to their measurements,
recorded in a pair of measurement name and the index of measurement schemas
(this.measurementSchemas).

@return map from device path to its measurements.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/statement/crud/InsertBaseStatement.java