stagesupport/src/main/java/com/streamsets/pipeline/config/upgrade/DataFormatUpgradeHelper.java
public static void ensureAvroSchemaExists(List<Config> configs, String prefix) {
    Optional<Config> avroSchema = findByName(configs, "avroSchema");
    if (!avroSchema.isPresent()) {
      configs.add(new Config(prefix + ".avroSchema", null));
    }
  }
public static void ensureAvroSchemaExists(List<Config> configs, String prefix) {
    Optional<Config> avroSchema = findByName(configs, "avroSchema");
    if (!avroSchema.isPresent()) {
      configs.add(new Config(prefix + ".avroSchema", null));
    }
  }
There is a problem with some older stages that originally were not using our data parser library as the
upgrade on those stages does not create all the properties that were introduced by the data parser library.
For example File Tail origin doesn't support avro, so the upgrade procedure doesn't use create the avro
specific properties. This is normally not a problem as post-upgrade SDC will create all missing properties
with default values. However this particular upgrade will fail if the property avroSchema is missing.

Hence for such stages, this method will ensure that the property avroSchema is properly present. The migration
to data parser library happened for majority of stages in 1.2 release and hence this really affects only people
upgrading from 1.1.x all the way to 2.1 or above. If the user upgraded from 1.1.x and then to any other release
below 2.1 first, they would not hit this issue as the property avroSchema would be added with default value.