CAMEL-22090: Fix couchbase consumer when Jackson is on classpath

[gnodet]

Summary

• Fixed the Couchbase consumer to avoid using the shaded Jackson JsonNode class for view key deserialization, using String.class instead which works regardless of which Jackson serializer is active
• Extracted ClusterEnvironment creation into a dedicated createClusterEnvironment() method with documentation explaining why DefaultJsonSerializer is explicitly configured to prevent the Couchbase SDK from auto-detecting non-shaded Jackson on the classpath
• Added a unit test verifying the ClusterEnvironment uses DefaultJsonSerializer (wrapped in JsonValueSerializerWrapper) instead of the auto-detected JacksonJsonSerializer

Details

When Jackson is on the classpath (e.g., via camel-jackson, Spring Boot, or Quarkus), the Couchbase SDK auto-detects it and uses JacksonJsonSerializer backed by the non-shaded Jackson ObjectMapper. This causes deserialization failures because the consumer code was using row.keyAs(JsonNode.class) where JsonNode is the shaded class (com.couchbase.client.core.deps.com.fasterxml.jackson.databind.JsonNode), which the non-shaded Jackson cannot deserialize into.

The fix addresses this at two levels:

1. Consumer level: Replaced row.keyAs(JsonNode.class).get().asText() with row.keyAs(String.class).orElse(null), eliminating the dependency on shaded Jackson types for key extraction
2. Environment level: Kept the DefaultJsonSerializer configuration (from CAMEL-22083) but refactored it into a well-documented, testable method

Test plan

• Unit tests pass (27 tests, 0 failures)
• Integration tests with Couchbase container (require testcontainers)
• Manual verification with Jackson on the classpath

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[gnodet]

Note: DefaultJsonSerializer (which uses the shaded Jackson) was already explicitly configured in the existing code. The real fix here is changing row.keyAs(JsonNode.class).get().asText() to row.keyAs(String.class).orElse(null) in the consumer, which avoids depending on the shaded JsonNode class entirely.

There is no valid use case for users wanting the Couchbase SDK to use non-shaded Jackson, since all SDK internal types depend on the shaded version. Using String.class for view row keys is safe — keys are typically strings or simple JSON values, and the result is set as a String header anyway.

The endpoint method extraction (createClusterEnvironment()) is optional refactoring for testability but not strictly needed for the fix.