[JAVA-SPRING] Convert byte[] to String for operation params [QueryParam; PathParam; HeaderParam; CookieParam; FormParam] #22930

Picazsoo · 2026-02-09T21:45:43Z

This change updates the generator to correctly map OpenAPI format: byte fields across all locations.

Query, Path, Header, Cookie, and Form fields: format: byte is generated as String (manual Base64 decoding required).
Multipart text fields: String.
Multipart file fields (format: binary): MultipartFile.
JSON request body DTO fields: byte[], with automatic Base64 decoding via Jackson.
Raw binary request bodies (application/octet-stream): Resource for streaming, no decoding applied.

This ensures all format: byte values are correctly typed across parameters and bodies, preserving the distinction between Base64-encoded values and raw binary.

The changes are practically limited to QueryParam; PathParam; HeaderParam; CookieParam; FormParam. But all the other types are asserted as well to prevent accidental regression.

fixes #22898

Tests performed:

Verified generated Java files for query, path, header, cookie, form, multipart, JSON body, and binary body fields.

Asserts confirm parameters and properties have the expected types (String, byte[], MultipartFile, Resource).

PR checklist

Read the contribution guidelines.
Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
Run the following to build the project and update samples:
```
./mvnw clean package || exit
./bin/generate-samples.sh ./bin/configs/*.yaml || exit
./bin/utils/export_docs_generators.sh || exit
```
(For Windows users, please run the script in WSL)
Commit all changed files.
This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
These must match the expectations made by your contribution.
You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
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Summary by cubic

Converted byte[] operation parameters to String in the Java Spring generator for query, path, header, cookie, and form params. Spring doesn’t auto-decode base64 here, so we accept the raw base64 string to avoid type issues.

Bug Fixes
- Map byte[] params in query/path/header/cookie/form to String via SpringCodegen (convertByteArrayParamsToStringType); templates add “base64 encoded binary” comments.
- Preserve ByteArray → byte[] for models and JSON bodies; raw binary bodies remain Resource; multipart binary fields use MultipartFile. Explicit ByteArray → byte[] mapping added in AbstractJavaCodegen.
- Added tests and new OAS fixtures; added a Spring Boot sample (springboot-byte-format-edge-cases) and wired it into CI; regenerated affected samples.
Migration
- If you previously used byte[] for these params, decode the provided base64 String yourself (e.g., Base64.getDecoder().decode(value)).

^{Written for commit e0d2d56. Summary will update on new commits.}

cubic-dev-ai

2 issues found across 41 files

Prompt for AI agents (all issues)


Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="samples/server/petstore/springboot-reactive-noResponseEntity/src/main/java/org/openapitools/api/FakeApi.java">

<violation number="1" location="samples/server/petstore/springboot-reactive-noResponseEntity/src/main/java/org/openapitools/api/FakeApi.java:383">
P2: @RequestPart is for multipart/form-data, but this endpoint consumes application/x-www-form-urlencoded. The modified parameter still uses @RequestPart, so WebFlux won’t bind the form body correctly (likely 400).</violation>
</file>

<file name="modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java">

<violation number="1" location="modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java:944">
P2: Form/multipart DTO still asserts `format: byte` as `byte[]`, but Spring’s default data binding does not Base64‑decode form strings to `byte[]`; it converts the string to raw bytes. This makes form DTO binding inconsistent with the new `String` parameter handling and can yield incorrect values without a custom converter.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

...etstore/springboot-reactive-noResponseEntity/src/main/java/org/openapitools/api/FakeApi.java

.../openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java

cubic-dev-ai

2 issues found across 33 files (changes from recent commits).

Prompt for AI agents (all issues)


Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="samples/server/petstore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java">

<violation number="1" location="samples/server/petstore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java:16">
P2: RFC3339DateFormat hardcodes the delegate StdDateFormat to UTC and does not override setTimeZone, so any configured timezone will be ignored and dates will always format in UTC.</violation>

<violation number="2" location="samples/server/petstore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java:36">
P2: clone() returns the same instance instead of a copy, violating the Format/DateFormat clone contract and preventing callers from obtaining an independent DateFormat instance.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

cubic-dev-ai · 2026-02-10T08:38:25Z

...tore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java

+  private static final long serialVersionUID = 1L;
+  private static final TimeZone TIMEZONE_Z = TimeZone.getTimeZone("UTC");
+
+  private final StdDateFormat fmt = new StdDateFormat()


P2: RFC3339DateFormat hardcodes the delegate StdDateFormat to UTC and does not override setTimeZone, so any configured timezone will be ignored and dates will always format in UTC.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At samples/server/petstore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java, line 16: <comment>RFC3339DateFormat hardcodes the delegate StdDateFormat to UTC and does not override setTimeZone, so any configured timezone will be ignored and dates will always format in UTC.</comment> <file context> @@ -0,0 +1,38 @@ + private static final long serialVersionUID = 1L; + private static final TimeZone TIMEZONE_Z = TimeZone.getTimeZone("UTC"); + + private final StdDateFormat fmt = new StdDateFormat() + .withTimeZone(TIMEZONE_Z) + .withColonInTimeZone(true); </file context>

cubic-dev-ai · 2026-02-10T08:38:25Z

...tore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java

+
+  @Override
+  public Object clone() {
+    return this;


P2: clone() returns the same instance instead of a copy, violating the Format/DateFormat clone contract and preventing callers from obtaining an independent DateFormat instance.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At samples/server/petstore/springboot-byte-format-edge-cases/src/main/java/org/openapitools/RFC3339DateFormat.java, line 36: <comment>clone() returns the same instance instead of a copy, violating the Format/DateFormat clone contract and preventing callers from obtaining an independent DateFormat instance.</comment> <file context> @@ -0,0 +1,38 @@ + + @Override + public Object clone() { + return this; + } +} </file context>

Picazsoo added 2 commits February 9, 2026 22:43

convert byte[] to String for operation params

59bd0eb

add unit tests

78499b6

Picazsoo marked this pull request as ready for review February 9, 2026 22:51

clean up open api spec

02a530a

cubic-dev-ai bot reviewed Feb 9, 2026

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...etstore/springboot-reactive-noResponseEntity/src/main/java/org/openapitools/api/FakeApi.java Outdated Show resolved Hide resolved

.../openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java Show resolved Hide resolved

Picazsoo added 3 commits February 10, 2026 09:07

fix CR suggestions

8685cb9

add sample

e78800b

add sample and fix log

6e37d4e

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[JAVA-SPRING] Convert byte[] to String for operation params [QueryParam; PathParam; HeaderParam; CookieParam; FormParam] #22930

[JAVA-SPRING] Convert byte[] to String for operation params [QueryParam; PathParam; HeaderParam; CookieParam; FormParam] #22930

Picazsoo commented Feb 9, 2026 •

edited by cubic-dev-ai bot

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Picazsoo commented Feb 9, 2026 •

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