cdm/src/main/java/ucar/nc2/dataset/StructureDS.java
private boolean convertNeeded(StructureMembers smData) {

    for (Variable v : getVariables()) {

      if (v instanceof VariableDS) {
        VariableDS vds = (VariableDS) v;
        if (vds.needConvert())
          return true;
      } else if (v instanceof StructureDS) {
        StructureDS nested = (StructureDS) v;
        if (nested.convertNeeded(null))
          return true;
      }

      // a variable with no data in the underlying smData
      if ((smData != null) && !varHasData(v, smData))
        return true;
    }

    return false;
  }
private boolean convertNeeded(StructureMembers smData) {

    for (Variable v : getVariables()) {

      if (v instanceof VariableDS) {
        VariableDS vds = (VariableDS) v;
        if (vds.needConvert())
          return true;
      } else if (v instanceof StructureDS) {
        StructureDS nested = (StructureDS) v;
        if (nested.convertNeeded(null))
          return true;
      }

      // a variable with no data in the underlying smData
      if ((smData != null) && !varHasData(v, smData))
        return true;
    }

    return false;
  }
is conversion needed?