[Java][Native] Fix request compression

[inemtsev]

During testing of the newly added Gzip feature for Java+native template, we discovered that request was missing the gzip header in the stream because it was being cleared by the buffer.reset() method. This PR:

• Fixes the missing gzip header by applying it after the reset.
• Increase the size of decompression buffer to 8KB from 512bytes default. 512 bytes is tiny, competing Http clients like OkHttp and Apache use 8KB by default.

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---

Summary by cubic

Fixes gzip request compression in the Java native client so the gzip header is preserved. Also enables streaming gzip for requests and uses an 8KB buffer for response decompression.

• Bug Fixes

  • Initialize gzip after buffer.reset to keep the gzip header in the stream.
  • Return 0 on zero-length read in the gzip stream to match InputStream contract.

• New Features

  • Stream gzip request bodies via ApiClient.gzipRequestBody and set Content-Encoding/Accept-Encoding headers; enabled via useGzipFeature in config.
  • Use an 8KB GZIPInputStream buffer for response decompression.

^{Written for commit 6293788. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 4 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/client/petstore/java/native-useGzipFeature/src/main/java/org/openapitools/client/ApiClient.java">

<violation number="1" location="samples/client/petstore/java/native-useGzipFeature/src/main/java/org/openapitools/client/ApiClient.java:564">
P2: read(byte[],off,len) violates InputStream contract by returning -1 on zero-length reads at EOF instead of 0</violation>
</file>

---

Since this is your first cubic review, here's how it works:

• cubic automatically reviews your code and comments on bugs and improvements
• Teach cubic by replying to its comments. cubic learns from your replies and gets better over time
• Ask questions if you need clarification on any suggestion

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

[cubic-dev-ai]

1 issue found across 4 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="modules/openapi-generator/src/main/resources/Java/libraries/native/ApiClient.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/Java/libraries/native/ApiClient.mustache:573">
P2: read(byte[],off,len) now returns 0 for len==0 without null/bounds validation, diverging from InputStream contract and masking invalid arguments</violation>
</file>

---

Since this is your first cubic review, here's how it works:

• cubic automatically reviews your code and comments on bugs and improvements
• Teach cubic by replying to its comments. cubic learns from your replies and gets better over time
• Ask questions if you need clarification on any suggestion

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

[cubic-dev-ai]

P2: read(byte[],off,len) now returns 0 for len==0 without null/bounds validation, diverging from InputStream contract and masking invalid arguments

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At modules/openapi-generator/src/main/resources/Java/libraries/native/ApiClient.mustache, line 573:

<comment>read(byte[],off,len) now returns 0 for len==0 without null/bounds validation, diverging from InputStream contract and masking invalid arguments</comment>

<file context>
@@ -570,6 +570,9 @@ public class ApiClient {
 
     @Override
     public int read(byte[] b, int off, int len) throws IOException {
+      if (len == 0) {
+        return 0;
+      }
</file context>

Suggested change

	if (len == 0) {
	return 0;
	}
	Objects.requireNonNull(b, "buffer must not be null");
	if (off < 0 || len < 0 || len > b.length - off) {
	throw new IndexOutOfBoundsException();
	}
	if (len == 0) {
	return 0;
	}

[inemtsev]

Good suggestion, I have fixed this edge-case

[inemtsev]

Ready to go from my side.

[wing328]

@inemtsev thanks for the PR

may I confirm with you that you've tested this change (the latest one after incorporating feedback from cubic-dev-ai) locally to confirm it works for your use cases?