HDDS-10542. Replace remaining GSON usage with Jackson.

[ArafatKhan2198]

What changes were proposed in this pull request?

This pull request introduces a migration from Gson to Jackson, specifically focusing on replacing Gson's JsonParser with Jackson's ObjectMapper. It involves using ObjectMapper's readValue() method to deserialize JSON strings into Java objects. Additionally, the code utilizes Jackson's JsonNode to navigate and extract data from JSON structures.

Important mention ➖

We also improved the JsonUtils class by introducing new utility methods for more flexible JSON processing with Jackson. We added readArrayFromReader to deserialize JSON content from a Reader into Java arrays, and convertValueOrObjectNode to efficiently convert any given value into a JsonNode, ensuring compatibility with various JSON structures. These improvements streamline JSON operations across our project, for both serialization and deserialization tasks.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-10542

How was this patch tested?

Ran the Unit Tests for the changed classes.
The forked CI also ran green!

[adoroszlai]

Thanks @ArafatKhan2198 for working on this.

[adoroszlai]

@ArafatKhan2198 Let's remove changes related to EventQueue from this patch, and address that in a follow-up task.

[ArafatKhan2198]

@ArafatKhan2198 Let's remove changes related to EventQueue from this patch, and address that in a follow-up task.

Ok will remove.

But I did try a bunch of things, from the error The InvalidDefinitionException suggests that Jackson attempted to serialize an instance of UnknownFieldSet$Parser, which likely does not have any properties Jackson can serialize directly. Reading a little about it might happen because of protobuf classes.

One quick fix i tried to implement was that ➖

• Disable FAIL_ON_EMPTY_BEANS: As a quick fix, I can configure our ObjectMapper to not fail on empty beans. This tells Jackson to output an empty JSON object ({}) instead of throwing an exception when it encounters a type with no properties to serialize.

objectMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);

• We could also use @JsonIgnoreProperties to filter and ignore certain properties or classes when serializing. But not sure what we could ignore there.Earlier in this class gson was using a custom serializer to ignore serialising for the parent field in the NodeImpl class. Jackson does not inherently support exclusion strategies like Gson's ExclusionStrategy, which dynamically includes or excludes fields from serialization at runtime. Instead, to achieve similar functionality, we have used the @JsonIgnore in the NodeImpl class annotation directly on fields we wish to exclude. Could it have been not implemented properly and this field might throw error?

patch updated

[szetszwo]

@ArafatKhan2198 , thanks for working on this!

• We should add the test methods to src/test.
• This change is very big (64kb). Please split it into at least two JIRAs. We may have the hadoop-hdds first and then then hadoop-ozone changes.

[devmadhuu]

@ArafatKhan2198 thanks for working on this patch, few comments. Pls check.

[szetszwo]

@ArafatKhan2198 , thanks for the update! Please see the comments inlined and also https://issues.apache.org/jira/secure/attachment/13068634/6500_review.patch

BTW, please don't use wrap short lines (lines < 80 chars). Our max line length is 120 chars.

[szetszwo]

@ArafatKhan2198 , thanks for the update. The change looks good.

• Please address @devmadhuu 's comment on isMissing(). I also have a question there.
• Please don't use short lines for the new code.

[ArafatKhan2198]

@szetszwo @devmadhuu We should be good to go on this, let me know if there are any other changes.

[devmadhuu]

Thanks @ArafatKhan2198 for working on this patch. LGTM +1

[szetszwo]

+1 the change looks good.

[szetszwo]

@ArafatKhan2198 , thanks for your contribution!

@devmadhuu , thanks a lot for reviewing this!