shashank created CAMEL-25360:
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Summary: camel-cloudevents - application-cloudevents+json ignores
the datacontenttype when it writes the data: JSON of a text/plain body is
nested, JSON scalars are strings, bytes that are not valid text are lost
Key: CAMEL-25360
URL: https://issues.apache.org/jira/browse/CAMEL-25360
Project: Camel
Issue Type: Bug
Reporter: shashank
The {{application-cloudevents+json}} data type
({{CloudEventJsonDataTypeTransformer}}) decides how to write the body as the
{{data}} of the event from the body alone: a body that is a JSON object or
array is nested, anything else is a JSON string. The CloudEvents JSON format
(section 3.1) decides by the {{datacontenttype}}: data whose content type is
JSON ({{*/json}}, {{*/*+json}}, and {{application/json}} when it is absent) is
a JSON value, other data is a string, and binary data is written Base64 encoded
as {{data_base64}}. So:
* a {{text/plain}} (or {{application/octet-stream}}) body {{[1,2]}} is written
as {{"data":[1,2]}} instead of {{"data":"[1,2]"}}. CloudEvents readers reject
such an event: the CloudEvents Java SDK ({{CloudEventDeserializer}}) fails with
"Because content type is not a json, only a string is accepted as data";
* under {{application/json}} (also the default), a body {{42}}, {{true}},
{{null}} or {{"text"}} is written as a string ({{"data":"42"}},
{{"data":"\"text\""}}), not as the JSON value;
* a {{byte[]}} body that is not valid text is decoded as text into {{data}},
which replaces every invalid byte, so the data is lost.
In the review of #27342 Claus Ibsen listed these three as an optional
follow-up; they predate CAMEL-25301.
h3. Reproduction
{{CloudEventJsonDataTypeTransformerTest}} (new tests), failing on main:
{{shouldNotNestJsonDataOfANonJsonContentType}} ({{expected: <[1,2]> but was:
<[1, 2]>}}, a JSON array), {{shouldUseTheDataContentTypeOfTheEvent}} (the
{{CamelCloudEventDataContentType}} header {{text/plain}}),
{{shouldNestJsonScalarsOfAJsonContentType}} ({{expected: BigDecimal<42> but
was: String<42>}}), {{shouldWriteBinaryDataAsBase64}} and
{{shouldWriteBytesThatAreNotValidTextAsBase64WhateverTheContentType}} (no
{{data_base64}}),
{{shouldWriteBytesThatAreValidTextAsStringWhenTheContentTypeIsBinary}} (a JSON
{{byte[]}} body declared {{application/octet-stream}} is nested).
h3. Proposed fix
Decide by the {{datacontenttype}} of the event
({{CamelCloudEventDataContentType}}, else {{Content-Type}}, else
{{application/json}}):
* JSON media type (subtype {{json}} or suffix {{+json}}, parameters and case
ignored): a body that is a JSON value, now including a scalar, is nested; any
other body is a string (as the scan from CAMEL-25301 already does for malformed
JSON). Without a content type this is the default, so the default behaviour
stays: JSON objects and arrays nested, other text as a string; only scalar
bodies change.
* any other content type: the body is a string, also a JSON object or array.
* a {{byte[]}} body that is not valid text in the charset of the exchange
(UTF-8 by default), whatever the content type: {{data_base64}}. A {{byte[]}}
body that is valid text is written as text as before; valid UTF-8 written as a
JSON string gives a reader the same bytes back. Other bodies (an
{{InputStream}}, a stream cache) are read as text as before.
Controls: a JSON {{byte[]}} body under {{application/json}} is nested and a
{{text/plain}} {{byte[]}} body is text, as before; malformed JSON under
{{application/json}} stays a string; {{application/vnd.example+json;
charset=UTF-8}} and {{Application/JSON}} are JSON; {{byte[]}} bodies are
decoded in the charset of the exchange. Module: 24 tests pass.
Impact on component data types (upgrade guide): several CloudEvent data types
declare a fixed content type that is not JSON, whatever the body is:
{{aws2-s3}}, {{aws2-kinesis}}, {{google-pubsub}}, {{azure-eventhubs}},
{{azure-storage-blob}} and others declare {{application/octet-stream}} (since
CAMEL-20334 for aws2-s3), {{aws-cloudtrail}}, {{azure-storage-queue}} and
{{azure-cosmosdb}} declare {{text/plain}}. Followed by
{{application-cloudevents+json}}, a JSON body of such a message (a CloudTrail
event always is one) is now a JSON string instead of nested. This narrows the
nesting of CAMEL-22339 to JSON content types. The upgrade guide says how to
keep a JSON body nested (set {{CamelCloudEventDataContentType}} to
{{application/json}}). No Kamelet in camel-kamelets uses
{{application-cloudevents+json}} (GitHub code search, 2026-10-05); a Pipe to
Knative such as the one in CAMEL-20334 uses the binary mode
({{http:application-cloudevents}}), which this does not change.
Affected: 4.14.x, 4.18.x and main.
Duplicate check (2026-10-05): JIRA "CloudEventJsonDataTypeTransformer"
(CAMEL-25301 only), "datacontenttype" (CAMEL-25301, CAMEL-20334), "data_base64"
(none). GitHub pull requests "datacontenttype": only #27342; no open PR on
camel-cloudevents.
_Filed with Claude Code on behalf of allthingssecurity._
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