feat: support OkHttp application interceptors

openai-java-client-okhttp/build.gradle.kts

@@ -21,7 +21,7 @@ listOf(configurations.testCompileClasspath, configurations.testRuntimeClasspath)
 dependencies {
     api(project(":openai-java-core"))
 
-    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+    api("com.squareup.okhttp3:okhttp:4.12.0")
 
     testImplementation(kotlin("test"))
     testImplementation("org.assertj:assertj-core:3.27.7")

openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OkHttpClient.kt

@@ -29,6 +29,7 @@ import okhttp3.ConnectionPool
 import okhttp3.Dispatcher
 import okhttp3.HttpUrl
 import okhttp3.HttpUrl.Companion.toHttpUrl
+import okhttp3.Interceptor
 import okhttp3.MediaType
 import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.Request
@@ -120,6 +121,7 @@ internal constructor(@JvmSynthetic internal val okHttpClient: okhttp3.OkHttpClie
         private var sslSocketFactory: SSLSocketFactory? = null
         private var trustManager: X509TrustManager? = null
         private var hostnameVerifier: HostnameVerifier? = null
+        private val interceptors: MutableList<Interceptor> = mutableListOf()
 
         fun timeout(timeout: Timeout) = apply { this.timeout = timeout }
 
@@ -136,6 +138,9 @@ internal constructor(@JvmSynthetic internal val okHttpClient: okhttp3.OkHttpClie
             this.proxyAuthenticator = proxyAuthenticator
         }
 
+        /** Adds an application interceptor to the underlying OkHttp transport. */
+        fun addInterceptor(interceptor: Interceptor) = apply { interceptors.add(interceptor) }
+
         /**
          * Sets the maximum number of idle connections kept by the underlying [ConnectionPool].
          *
@@ -187,6 +192,8 @@ internal constructor(@JvmSynthetic internal val okHttpClient: okhttp3.OkHttpClie
                     .callTimeout(timeout.request())
                     .proxy(proxy)
                     .apply {
+                        interceptors.forEach(::addInterceptor)
+
                         proxyAuthenticator?.let { auth ->
                             proxyAuthenticator { route, response ->
                                 auth

openai-java-client-okhttp/src/test/kotlin/com/openai/client/okhttp/OkHttpClientTest.kt

@@ -5,6 +5,7 @@ import com.github.tomakehurst.wiremock.junit5.WireMockRuntimeInfo
 import com.github.tomakehurst.wiremock.junit5.WireMockTest
 import com.openai.core.http.HttpMethod
 import com.openai.core.http.HttpRequest
+import okhttp3.Interceptor
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
@@ -41,4 +42,40 @@ internal class OkHttpClientTest {
         // Should have cancelled the underlying call
         assertThat(call.isCanceled()).isTrue()
     }
+
+    @Test
+    fun execute_runsConfiguredApplicationInterceptor() {
+        stubFor(get(urlPathEqualTo("/something")).willReturn(ok()))
+        val client =
+            OkHttpClient.builder()
+                .addInterceptor(
+                    Interceptor { chain ->
+                        chain.proceed(
+                            chain
+                                .request()
+                                .newBuilder()
+                                .header("X-Test-Interceptor", "applied")
+                                .build()
+                        )
+                    }
+                )
+                .build()
+
+        client
+            .execute(
+                HttpRequest.builder()
+                    .method(HttpMethod.GET)
+                    .baseUrl(baseUrl)
+                    .addPathSegment("something")
+                    .build()
+            )
+            .use { assertThat(it.statusCode()).isEqualTo(200) }
+
+        verify(
+            1,
+            getRequestedFor(urlPathEqualTo("/something"))
+                .withHeader("X-Test-Interceptor", equalTo("applied")),
+        )
+        client.close()
+    }
 }