feat: [OpenAPI] `ResponseMetadataListener` with case insensitive header map #1070

rpanackal · 2026-01-16T14:39:54Z

Context

SAP/cloud-sdk-java-backlog#464.

Feature scope:

Introduce a ResponseMetadataListener that accepts OpenApiResponse object which includes the metadata
Make case insensitive key match for headers using TreeMap

Definition of Done

Functionality scope stated & covered
Tests cover the scope above
~~Error handling created / updated & covered by the tests above~~
~~Documentation updated~~
~~Release notes updated~~

This reverts commit 888bc4d.

- models only

- formatting - add api classes

- no more shared client in *Api.java instances

… apiclient package

…eAPI`

- *Api.invoke method bugged and unused

- Remove debugging, connectionTimeout, defaultHeaderMap, defaultCookieMap - add TODOs - public setBasePath - Remove addDefaultHeader, setUserAgent,

- Make as manny methods static - Remove deprecated getStatusCode and getResponseHeaders - public parameterToPairs

- Make as many methods static - rename ApiClientResponseHandler to DefaultApiResponseHandler - finish up ApiClient todos

…-generator/mustache-templates/libraries/apache-httpclient/api.mustache Co-authored-by: Charles Dubois <103174266+CharlesDuboisSAP@users.noreply.github.com>

…e' into feat/openapi/optional-spring-base

…/services/openapi/apache/ApiClient.java Co-authored-by: Charles Dubois <103174266+CharlesDuboisSAP@users.noreply.github.com>

…st-apache-client-templates # Conflicts: # datamodel/openapi/openapi-generator/src/main/resources/openapi-generator/mustache-templates/libraries/apache-httpclient/api.mustache

…#1062) Moving to single larger PR (sorry), because its getting difficult to sync changes across. Both PRs have been thoroughly review at this point.

…sponse-status-and-header # Conflicts: # datamodel/openapi/openapi-generator/src/main/resources/openapi-generator/mustache-templates/libraries/apache-httpclient/operationBody.mustache # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-for-ai-sdk/output/com/sap/cloud/sdk/services/builder/api/AwesomeSodaApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-for-ai-sdk/output/com/sap/cloud/sdk/services/builder/api/AwesomeSodasApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-for-ai-sdk/output/com/sap/cloud/sdk/services/builder/api/DefaultApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-vendor-extension-json/output/com/sap/cloud/sdk/services/apiclassvendorextension/api/AwesomeSodaApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-vendor-extension-json/output/com/sap/cloud/sdk/services/apiclassvendorextension/api/AwesomeSodasApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-vendor-extension-json/output/com/sap/cloud/sdk/services/apiclassvendorextension/api/DefaultApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/api-class-vendor-extension-yaml/output/com/sap/cloud/sdk/services/apiclassvendorextension/api/DefaultApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/inlineobject-schemas-enabled/output/com/sap/cloud/sdk/services/inlineobject/api/DefaultApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/partial-generation/output/com/sap/cloud/sdk/services/builder/api/DefaultApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/remove-operation-id-prefix/output/com/sap/cloud/sdk/services/builder/api/OrdersApi.java # datamodel/openapi/openapi-generator/src/test/resources/DataModelGeneratorApacheIntegrationTest/remove-operation-id-prefix/output/com/sap/cloud/sdk/services/builder/api/SodasApi.java

# Conflicts: # datamodel/openapi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/ApiClient.java # datamodel/openapi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/DefaultApiResponseHandler.java # datamodel/openapi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/OpenApiResponse.java

rpanackal · 2026-01-16T14:43:12Z

...pi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/OpenApiResponse.java

-    OpenApiResponse( final int statusCode, @Nonnull final Map<String, List<String>> headers )
-    {
-        this.statusCode = statusCode;
-        this.headers = Map.copyOf(headers);


Map.copy() doesn't return a TreeMap and therefore removes the nice case insensitive matching of headers. Instead I opted to make the treeMap unmodifiable at creation site with Collections.unmodifiableMap()

rpanackal · 2026-01-16T14:44:24Z

...i-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/ResponseMetadataListener.java

+@FunctionalInterface
+public interface ResponseMetadataListener
+{
+    void onResponse( OpenApiResponse response );


I could create a new class OpenApiResponseMetadata or similar instead of re-using or maybe even abusing OpenApiResponse class. What do you think?

sap-email-compliance · 2026-01-16T14:45:37Z

SAP employees are expected to use their SAP-email address for commits related to their work. Our compliance check has detected usage of an email other than a SAP one by a SAP employee. Please update your pull request accordingly.

If you think this is wrong or need any assistance, please contact ospo@sap.com.

newtork · 2026-01-16T18:02:38Z

...i-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/ResponseMetadataListener.java

+ * @since 5.25.0
+ */
+@FunctionalInterface
+public interface ResponseMetadataListener


(Minor/Nitpick)

ResponseMetadataListener isn't very easy name.
What would you think of OpenApiResponseListener?

newtork

Apart from minor question regarding naming: looks good!

Jonas-Isr · 2026-01-19T10:47:01Z

.../openapi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/ApiClient.java


    @With
-    private final ResponseMetadataListener responseMetadataListener;
+    private final OpenApiResponseListener responseMetadataListener;


(Very Minor/Question)

Would it make sense to also rename the variable to openApiResponseListener to make it more consistent? (Same in DefaultApiResponseHandler.)

Jonas-Isr

LGTM

newtork · 2026-01-20T09:22:49Z

.../openapi/openapi-core/src/main/java/com/sap/cloud/sdk/services/openapi/apache/ApiClient.java


    @With
-    private final ResponseMetadataListener responseMetadataListener;
+    private final OpenApiResponseListener openApiResponseListener;


(Minor)

Could we add the @Beta annotation here?

While I'm okay with current state, I feel like having options in the future would be nice:

rename it, e.g. to withResponseListener

extend interface API, e.g. with HttpResponse reference, settings for error handling

rpanackal added 30 commits December 10, 2025 13:41

Move resttemplate moustache into dedicated folder

888bc4d

Revert "Move resttemplate moustache into dedicated folder"

3473fff

This reverts commit 888bc4d.

Add apache-httpclient/api.moustache

7991ce9

openapi apache sample

6638e7a

- models only

remove `@Generated

c08ceb6

Add apache-client common generated classes and dependency

a697b6e

dependency and formatting

28e8135

Add all required file (pruned later)

c3e438f

Fix dependencies

c934b1f

- formatting - add api classes

Simply api-apache-sample

ea0eeb6

Merge branch 'main' into feat/openapi/optional-spring-base

b81f4c2

Fix version issue

50a57bb

Pom config and exclusions

6a33cf6

Set format skip false for sample module

cde369f

regenerate with prompt-registry.yaml

7aed42d

regenerate with prompt-registry.yaml

d4747ad

Remove ServerVariable.java and ServerConfiguration.java files

03933a0

NoArgs ctor preserved but remove Configuration

27cc015

- no more shared client in *Api.java instances

Remove apache specific date classes addition. Reuse existing class in…

112360d

… apiclient package

Pair - Simplify and improve code quality

a9e609b

Remove Authentication classes and authNames from `ApiClient.invok…

2f684c6

…eAPI`

make unimported methods private and use ApacheHttpClient5Accessor

aa60080

Remove invokeAPI methods in BaseApi and *Api.java

73ffecc

- *Api.invoke method bugged and unused

Refactoring ApiClient

f4358bc

- Remove debugging, connectionTimeout, defaultHeaderMap, defaultCookieMap - add TODOs - public setBasePath - Remove addDefaultHeader, setUserAgent,

Refactoring ApiClient

3ce5400

- Make as manny methods static - Remove deprecated getStatusCode and getResponseHeaders - public parameterToPairs

Fix dependency and warning

ad8a738

Remove method overloading per operation with additionalHeaders

d8add74

Extract response handling out of ApiClient into ApiClientResponseHandler

0c0176c

Make static ApiClient ctors

db04109

- Make as many methods static - rename ApiClientResponseHandler to DefaultApiResponseHandler - finish up ApiClient todos

Remove ApiException and use enhanced OpenApiRequestException

ffada46

rpanackal and others added 18 commits January 13, 2026 11:07

fix oneOf serialization test

5f61ebf

Update datamodel/openapi/openapi-generator/src/main/resources/openapi…

4835a34

…-generator/mustache-templates/libraries/apache-httpclient/api.mustache Co-authored-by: Charles Dubois <103174266+CharlesDuboisSAP@users.noreply.github.com>

Review: Apache Method enum and ctor formatting

de76c72

Merge remote-tracking branch 'origin/feat/openapi/optional-spring-bas…

067ddc8

…e' into feat/openapi/optional-spring-base

Update datamodel/openapi/openapi-core/src/main/java/com/sap/cloud/sdk…

de01665

…/services/openapi/apache/ApiClient.java Co-authored-by: Charles Dubois <103174266+CharlesDuboisSAP@users.noreply.github.com>

Fix compliance issue and formatting

b7d623e

Merge branch 'feat/openapi/optional-spring-base' into feat/openapi/te…

16f26ab

…st-apache-client-templates # Conflicts: # datamodel/openapi/openapi-generator/src/main/resources/openapi-generator/mustache-templates/libraries/apache-httpclient/api.mustache

Make return statement always present

1226e6f

Merge branch 'feat/openapi/optional-spring-base' into feat/openapi/te…

4cf87b9

…st-apache-client-templates # Conflicts: # datamodel/openapi/openapi-generator/src/main/resources/openapi-generator/mustache-templates/libraries/apache-httpclient/api.mustache

Reeview changes

d8bc954

Case-insensitive header key match

f1216a9

minor changes in mustache files

d8a945e

feat: [OpenAPI] Part 2: Testing Apache Client Support and some fixes. (…

859a8f1

…#1062) Moving to single larger PR (sorry), because its getting difficult to sync changes across. Both PRs have been thoroughly review at this point.

Fix missed line on merge

f05242f

Add response metadata listener

27c7843

Test metadata listener and header lookup

587e038

rpanackal commented Jan 16, 2026

View reviewed changes

rpanackal added 2 commits January 16, 2026 15:47

Add missing javadoc

3c7ee80

Add missing javadoc

b75ed48

newtork reviewed Jan 16, 2026

View reviewed changes

newtork previously approved these changes Jan 16, 2026

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Rename to OpenApiResponseListener

b94ace5

rpanackal dismissed newtork’s stale review via b94ace5 January 19, 2026 09:30

Jonas-Isr reviewed Jan 19, 2026

View reviewed changes

Rename to OpenApiResponseListener

aa1f126

Jonas-Isr approved these changes Jan 19, 2026

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newtork reviewed Jan 20, 2026

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feat: [OpenAPI] `ResponseMetadataListener` with case insensitive header map #1070

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rpanackal commented Jan 16, 2026

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rpanackal commented Jan 16, 2026

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Feature scope:

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