[Java][okhttp-gson] support deserializing from InputStream instead of String to bypass 2GB Java String limit

[klin1344]

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__

Overview

Fixes issue kubernetes-client/java#4020 .

Makes two changes:

1. In okhttp-gson ApiClient, if we are deserializing JSON, get the response body as an InputStream instead of String for deserialization.
2. In JSON, add a new deserialize() method in which accepts InputStream.

These two changes enable the ApiClient to bypass the 2GB String length limit in Java and deserialize large responses greater than 2GB into Java objects.

Root Cause

When the response is too large, we get an error like this:

java.lang.IllegalArgumentException: byteCount: 2293832235
  at okio.Buffer.readString(Buffer.kt:306)
  at okio.Buffer.readString(Buffer.kt:302)
  at okio.RealBufferedSource.readString(RealBufferedSource.kt:96)
  at okhttp3.ResponseBody.string(ResponseBody.kt:187)
  at io.kubernetes.client.openapi.ApiClient.deserialize(ApiClient.java:758)
  at io.kubernetes.client.openapi.ApiClient.handleResponse(ApiClient.java:978)
  at io.kubernetes.client.openapi.ApiClient.execute(ApiClient.java:905)
  at io.kubernetes.client.informer.SharedInformerFactory$1.list(SharedInformerFactory.java:271)
  at io.kubernetes.client.informer.cache.ReflectorRunnable.run(ReflectorRunnable.java:91)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:358)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
  at java.lang.Thread.run(Thread.java:1583)

This issue occurs because the response body is converted to a String here in the ApiClient, which hits this validation in okhttp:

require(byteCount >= 0 && byteCount <= Integer.MAX_VALUE) { "byteCount: $byteCount" }

because of Java's String max length limit of Integer.MAX_VALUE which is 2^31 - 1.

[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/14587151272/job/40918080042?pr=21115

please update bin/utils/test_file_list.yaml according with new sha256 as the test file has been updated as part of this PR

[klin1344]

https://github.com/OpenAPITools/openapi-generator/actions/runs/14587151272/job/40918080042?pr=21115

please update bin/utils/test_file_list.yaml according with new sha256 as the test file has been updated as part of this PR

@wing328 ah I missed that, thank you! I have updated the test_file_list.yaml with the new SHA256 now.

[wing328]

looks like a rebase failed and some other changes not authored by you are also included.

given that only a few elixir related changes (already merged into master) are included, we will accept these this time.

[lhotari]

This change misses the fallback logic:

openapi-generator/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache

Lines 193 to 201 in 2c7efda

	} catch (JsonParseException e) {
	// Fallback processing when failed to parse JSON form response body:
	// return the response body string directly for the String return type;
	if (returnType.equals(String.class)) {
	return (T) body;
	} else {
	throw (e);
	}
	}

.
Kubernetes client-java breaks in certain use cases because of this.

[klin1344]

This change misses the fallback logic:

openapi-generator/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache

Lines 193 to 201 in 2c7efda

	} catch (JsonParseException e) {
	// Fallback processing when failed to parse JSON form response body:
	// return the response body string directly for the String return type;
	if (returnType.equals(String.class)) {
	return (T) body;
	} else {
	throw (e);
	}
	}

.
Kubernetes client-java breaks in certain use cases because of this.

@lhotari thanks for the catch. Opened #22498 to fix