fix: copy contents of request body when converting to OAuth2HttpRequest

* current implementation read contents of buffer, making it impossible to get the request body from the MockWebServer.takeRequest() as it had already been consumed

Author: tommytroen

src/main/kotlin/no/nav/security/mock/oauth2/extensions/RecordedRequestExtensions.kt

@@ -4,4 +4,4 @@ import no.nav.security.mock.oauth2.http.OAuth2HttpRequest
 import okhttp3.mockwebserver.RecordedRequest
 
 fun RecordedRequest.asOAuth2HttpRequest(): OAuth2HttpRequest =
-    OAuth2HttpRequest(this.headers, this.method!!, this.requestUrl!!, this.body.readUtf8())
+    OAuth2HttpRequest(this.headers, this.method!!, this.requestUrl!!, this.body.copy().readUtf8())

src/test/kotlin/no/nav/security/mock/oauth2/MockOAuth2ServerTest.kt

@@ -7,10 +7,12 @@ import com.nimbusds.jwt.JWTClaimsSet
 import com.nimbusds.jwt.SignedJWT
 import com.nimbusds.oauth2.sdk.GrantType
 import com.nimbusds.oauth2.sdk.id.Issuer
+import io.kotest.matchers.shouldBe
 import java.net.URLEncoder
 import no.nav.security.mock.oauth2.extensions.verifySignatureAndIssuer
 import no.nav.security.mock.oauth2.http.OAuth2TokenResponse
 import no.nav.security.mock.oauth2.http.WellKnown
+import no.nav.security.mock.oauth2.testutils.post
 import no.nav.security.mock.oauth2.token.DefaultOAuth2TokenCallback
 import no.nav.security.mock.oauth2.token.OAuth2TokenProvider
 import okhttp3.Credentials
@@ -314,6 +316,35 @@ class MockOAuth2ServerTest {
         assertThat(accessToken.jwtClaimsSet.issuer).endsWith("default")
     }
 
+    @Test
+    fun takeRequestShouldReturnReceivedRequest() {
+        server.enqueueResponse(MockResponse().setResponseCode(200).setBody("ok"))
+        client.post(
+            server.baseUrl(),
+            mapOf(
+                "param1" to "value1"
+            )
+        ).body?.close()
+
+        val recordedRequest1 = server.takeRequest()
+        recordedRequest1.requestUrl shouldBe server.baseUrl()
+        recordedRequest1.body.readUtf8() shouldBe "param1=value1"
+
+        client.post(
+            server.tokenEndpointUrl("test"),
+            mapOf(
+                "client_id" to "client",
+                "client_secret" to "sec",
+                "grant_type" to "client_credentials",
+                "scope" to "scope1"
+            )
+        ).body?.close()
+
+        val recordedRequest2 = server.takeRequest()
+        recordedRequest2.requestUrl shouldBe server.tokenEndpointUrl("test")
+        recordedRequest2.body.readUtf8() shouldBe "client_id=client&client_secret=sec&grant_type=client_credentials&scope=scope1"
+    }
+
     @Test
     fun issueTokenDirectlyFromMockOAuth2Server() {
         val signedJWT: SignedJWT = server.issueToken(