message: Probably fixed only create java strings for non-null entries. doh.
diff: @@ -210,6 +210,9 @@ JNIEXPORT jobjectArray JNICALL Java_nl_cwi_da_duckdb_DuckDBNative_duckdb_1jdbc_1
  case TypeId::VARCHAR:
  varlen_data = env->NewObjectArray(row_count, env->FindClass("java/lang/String"), nullptr);
  for (idx_t row_idx = 0; row_idx < row_count; row_idx++) {
  + if (FlatVector::Nullmask(vec)[row_idx]) {
  + continue;
  + }
  env->SetObjectArrayElement(
  varlen_data, row_idx, env->NewStringUTF(((string_t *)FlatVector::GetData(vec))[row_idx].GetData()));
  }
  