diff --git a/server/src/test/java/org/cloudfoundry/identity/uaa/authentication/ClientParametersAuthenticationFilterTest.java b/server/src/test/java/org/cloudfoundry/identity/uaa/authentication/ClientParametersAuthenticationFilterTest.java
index 871958cf69c..13497ebf619 100644
--- a/server/src/test/java/org/cloudfoundry/identity/uaa/authentication/ClientParametersAuthenticationFilterTest.java
+++ b/server/src/test/java/org/cloudfoundry/identity/uaa/authentication/ClientParametersAuthenticationFilterTest.java
@@ -26,6 +26,7 @@
 import java.io.IOException;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.atLeast;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoInteractions;
@@ -83,5 +84,59 @@ public void testStoreClientAuthenticationMethod() throws IOException, ServletExc
 
         verifyNoInteractions(authenticationEntryPoint);
         verify(chain).doFilter(request, response);
+        verify(authenticationDetails, atLeast(1)).getAuthenticationMethod();
+    }
+
+    @Test
+    public void testStoreClientAuthenticationMethodNoDetails() throws IOException, ServletException {
+        ClientParametersAuthenticationFilter filter = new ClientParametersAuthenticationFilter();
+
+        AuthenticationEntryPoint authenticationEntryPoint = mock(AuthenticationEntryPoint.class);
+        filter.setAuthenticationEntryPoint(authenticationEntryPoint);
+        AuthenticationManager clientAuthenticationManager = mock(AuthenticationManager.class);
+        filter.setClientAuthenticationManager(clientAuthenticationManager);
+
+        Authentication authentication = mock(Authentication.class);
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        when(clientAuthenticationManager.authenticate(Mockito.any())).thenReturn(authentication);
+        when(authentication.isAuthenticated()).thenReturn(true);
+        when(authentication.getDetails()).thenReturn(null);
+
+        MockFilterChain chain = mock(MockFilterChain.class);
+        request.addHeader("Content-Type", MediaType.APPLICATION_FORM_URLENCODED_VALUE);
+        MockHttpServletResponse response = new MockHttpServletResponse();
+
+        filter.doFilter(request, response, chain);
+
+        verifyNoInteractions(authenticationEntryPoint);
+        verify(chain).doFilter(request, response);
+    }
+
+    @Test
+    public void testStoreClientAuthenticationMethodNoMethod() throws IOException, ServletException {
+        ClientParametersAuthenticationFilter filter = new ClientParametersAuthenticationFilter();
+
+        AuthenticationEntryPoint authenticationEntryPoint = mock(AuthenticationEntryPoint.class);
+        filter.setAuthenticationEntryPoint(authenticationEntryPoint);
+        AuthenticationManager clientAuthenticationManager = mock(AuthenticationManager.class);
+        filter.setClientAuthenticationManager(clientAuthenticationManager);
+
+        Authentication authentication = mock(Authentication.class);
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        UaaAuthenticationDetails authenticationDetails = mock(UaaAuthenticationDetails.class);
+        when(clientAuthenticationManager.authenticate(Mockito.any())).thenReturn(authentication);
+        when(authentication.isAuthenticated()).thenReturn(true);
+        when(authentication.getDetails()).thenReturn(authenticationDetails);
+        when(authenticationDetails.getAuthenticationMethod()).thenReturn(null);
+
+        MockFilterChain chain = mock(MockFilterChain.class);
+        request.addHeader("Content-Type", MediaType.APPLICATION_FORM_URLENCODED_VALUE);
+        MockHttpServletResponse response = new MockHttpServletResponse();
+
+        filter.doFilter(request, response, chain);
+
+        verifyNoInteractions(authenticationEntryPoint);
+        verify(chain).doFilter(request, response);
+        verify(authenticationDetails).getAuthenticationMethod();
     }
 }
diff --git a/server/src/test/java/org/cloudfoundry/identity/uaa/oauth/token/PkceEnhancedAuthorizationCodeTokenGranterTest.java b/server/src/test/java/org/cloudfoundry/identity/uaa/oauth/token/PkceEnhancedAuthorizationCodeTokenGranterTest.java
index 77fb53a532d..84d0cf067e3 100644
--- a/server/src/test/java/org/cloudfoundry/identity/uaa/oauth/token/PkceEnhancedAuthorizationCodeTokenGranterTest.java
+++ b/server/src/test/java/org/cloudfoundry/identity/uaa/oauth/token/PkceEnhancedAuthorizationCodeTokenGranterTest.java
@@ -26,7 +26,10 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.atMost;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 class PkceEnhancedAuthorizationCodeTokenGranterTest {
@@ -94,5 +97,17 @@ void getOAuth2AuthenticationMethod() throws PkceValidationException {
     when(oAuth2Request.getExtensions()).thenReturn(authMap);
     when(oAuth2Request.createOAuth2Request(any())).thenReturn(oAuth2Request);
     assertNotNull(granter.getOAuth2Authentication(requestingClient, tokenRequest));
+    verify(oAuth2Request, times(2)).getExtensions();
+  }
+
+  @Test
+  void getOAuth2AuthenticationNoMethod() throws PkceValidationException {
+    HashMap authMap = new HashMap();
+    authMap.put(ClaimConstants.CLIENT_AUTH_METHOD, null);
+    when(pkceValidationService.checkAndValidate(any(), any(), any())).thenReturn(true);
+    when(oAuth2Request.getExtensions()).thenReturn(authMap);
+    when(oAuth2Request.createOAuth2Request(any())).thenReturn(oAuth2Request);
+    assertNotNull(granter.getOAuth2Authentication(requestingClient, tokenRequest));
+    verify(oAuth2Request, atMost(1)).getExtensions();
   }
 }
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