I'm utilizing openapi-generator-maven-plugin to generate Java classes for an API. We are using Nimbus to help with some related interactions, e.g. authentication.

The use of the OpenAPI-generated classes is very simple and elegant, however, I find that I miss some helper methods (getters) for extracting the method (e.g. GET or POST...) and URL (e.g. /v1/ping) of the endpoints I'm accessing through the generated class.

My primary use case for the method and URL here is that they are required for me in my DPoP proof which I send alongside the access token (htm and htu claim).

Some mockup code of what I'd like to achieve:

ApiClient apiClient = new ApiClient();
SomeApi api = new SomeApi(apiClient);
prepareDpopProof(api.getMethodOfDoSomething(), apiClient.getBasePath() + api.getUrlOfDoSomething());
api.doSomething();

What I'm missing here from my current generated code is getMethodOfDoSomething() and getUrlOfDoSomething(). Is there some elegant way of "extracting" this from the generated code? I'd prefer not having to hardcode it and/or doing it manually.

My current plugin execution is fairly simple, so there may be several options I am unaware of:

<plugin>
    <groupId>.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>7.8.0</version>
    <executions>
        <execution>
            <id>some_api</id>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${basedir}/src/main/resources/openapi/some_api.json</inputSpec>
                <output>${project.build.directory}/generated</output>
                <generatorName>java</generatorName>
                <apiPackage>some.api.api</apiPackage>
                <modelPackage>some.api.model</modelPackage>
                <invokerPackage>some.api.client</invokerPackage>
                <configOptions>
                    <useJakartaEe>true</useJakartaEe>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

While my question primarily requests a getter, I expect that such an option may not exist. In that case, I am interested in alternative ways of getting the method and URL of endpoints, preferably least hacky and least hardcoded.

I'm utilizing openapi-generator-maven-plugin to generate Java classes for an API. We are using Nimbus to help with some related interactions, e.g. authentication.

The use of the OpenAPI-generated classes is very simple and elegant, however, I find that I miss some helper methods (getters) for extracting the method (e.g. GET or POST...) and URL (e.g. /v1/ping) of the endpoints I'm accessing through the generated class.

My primary use case for the method and URL here is that they are required for me in my DPoP proof which I send alongside the access token (htm and htu claim).

Some mockup code of what I'd like to achieve:

ApiClient apiClient = new ApiClient();
SomeApi api = new SomeApi(apiClient);
prepareDpopProof(api.getMethodOfDoSomething(), apiClient.getBasePath() + api.getUrlOfDoSomething());
api.doSomething();

What I'm missing here from my current generated code is getMethodOfDoSomething() and getUrlOfDoSomething(). Is there some elegant way of "extracting" this from the generated code? I'd prefer not having to hardcode it and/or doing it manually.

My current plugin execution is fairly simple, so there may be several options I am unaware of:

<plugin>
    <groupId>.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>7.8.0</version>
    <executions>
        <execution>
            <id>some_api</id>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${basedir}/src/main/resources/openapi/some_api.json</inputSpec>
                <output>${project.build.directory}/generated</output>
                <generatorName>java</generatorName>
                <apiPackage>some.api.api</apiPackage>
                <modelPackage>some.api.model</modelPackage>
                <invokerPackage>some.api.client</invokerPackage>
                <configOptions>
                    <useJakartaEe>true</useJakartaEe>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

While my question primarily requests a getter, I expect that such an option may not exist. In that case, I am interested in alternative ways of getting the method and URL of endpoints, preferably least hacky and least hardcoded.

• java
• openapi
• openapi-generator

2 Answers 2

Generator doesn't provide any metainformation.

You have to read your /src/main/resources/openapi/some_api.json and get it from there.

I think there may be multiple ways to achieve this, e.g. reflection, but I ended up using an Interceptor for the ApiClient. This worked well for my particular case, since the DPoP proof can be added to the original request inside the Interceptor. This original request knows both the "method" and "URL" of the API call, which are the values I wanted to have through getters.

Simplified layout:

DPoPInterceptor dpopInterceptor = new DPoPInterceptor();

OkHttpClient okHttpClient = new OkHttpClient.Builder()
        .addInterceptor(dpopInterceptor)
        .build();

apiClient = new ApiClient();
apiClient.setHttpClient(okHttpClient);

SomeApi api = new SomeApi(apiClient);
api.doSomething();

Where my DPoPInterceptor would, simplified, do something similar to this:

public class DPoPInterceptor implements Interceptor {

    @Override
    public @NotNull Response intercept(Chain chain) throws IOException {
        Request originalRequest = chain.request();

        String method = originalRequest.method();
        String url = originalRequest.url().toString();

        Request modifiedRequest = originalRequest.newBuilder()
        .header("Authorization", "DPoP " + SOME_ACCESS_TOKEN)
        .header("DPoP", generateDpopProof(method, url, SOME_DPOP_KEY)
        .build();

        return chain.proceed(modifiedRequest);
    }

}

Where, depending on your other layout, you may need to take in e.g. an access token or a DPoP key in your interceptor to generate the DPoP proof. You may also need to trim the query parameters from the URL of the original request.