ByteArray deserialization is broken

[ondrej-hrstka]

Expected Behavior

When having DTO with ByteArray property, it should be deserialized from Base64 string representation during HTTP call.

Actual Behaviour

The response from the http call is 400 with message "Failed to convert argument [testDto] for value [null] due to: Instantiation of [simple type, class com.example.TestDto] value failed for JSON property content due to missing (therefore NULL) value for creator parameter content which is a non-nullable type\n at [Source: UNKNOWN; byte offset: #UNKNOWN] (through reference chain: com.example.TestDto[\"content\"])"

DTO example:

data class TestDto(
    val content: ByteArray
)

HTTP call example:

curl -X POST --location "http://localhost:8080/deserialization" \
    -H "Content-Type: application/json" \
    -d "{
          \"content\": \"YWJj\"
        }"

Steps To Reproduce

Just run ./gradlew test in the example application.

Environment Information

• Mac OS X 12.3.1
• Java 17 Temurin, Kotlin 1.6.10

Example Application

https://github.com/ondrej-hrstka/bytearray-deserialization-issue

Version

3.4.2

[ondrej-hrstka]

OK,

so I've debuged this deeper, and the problem is that the JsonNodeTraversingParser#getBinaryValue returns always null. Source code is here:

micronaut-core/jackson-core/src/main/java/io/micronaut/jackson/core/tree/JsonNodeTraversingParser.java

Lines 259 to 261 in eec17c8

	public byte[] getBinaryValue(Base64Variant b64variant) throws IOException {
	return null;
	}

I can try prepare the fix PR, but I will get to it on Wednesday soonest. I've also added more specific test.