Fix tests in ClientRegistrationsTests

Issue gh-17542

Author: jgrandja

oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/registration/ClientRegistrationsTests.java

@@ -40,6 +40,7 @@
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.assertj.core.api.Assertions.assertThatNullPointerException;
 
 /**
  * @author Rob Winch
@@ -182,16 +183,14 @@ private void assertIssuerMetadata(ClientRegistration registration, ClientRegistr
 	@Test
 	public void issuerWhenResponseMissingJwksUriThenThrowsIllegalArgumentException() throws Exception {
 		this.response.remove("jwks_uri");
-		assertThatIllegalArgumentException().isThrownBy(() -> registration("").build())
-			.withMessageContaining("The public JWK set URI must not be null");
+		assertThatIllegalArgumentException().isThrownBy(() -> registration("").build());
 	}
 
 	// gh-7512
 	@Test
 	public void issuerWhenOidcFallbackResponseMissingJwksUriThenThrowsIllegalArgumentException() throws Exception {
 		this.response.remove("jwks_uri");
-		assertThatIllegalArgumentException().isThrownBy(() -> registrationOidcFallback("issuer1", null).build())
-			.withMessageContaining("The public JWK set URI must not be null");
+		assertThatIllegalArgumentException().isThrownBy(() -> registrationOidcFallback("issuer1", null).build());
 	}
 
 	// gh-7512
@@ -476,8 +475,7 @@ private ClientRegistration.Builder registration(Map<String, Object> configuratio
 	@Test
 	public void issuerWhenOidcConfigurationResponseMissingJwksUriThenThrowsIllegalArgumentException() throws Exception {
 		this.response.remove("jwks_uri");
-		assertThatIllegalArgumentException().isThrownBy(() -> registration(this.response).build())
-			.withMessageContaining("The public JWK set URI must not be null");
+		assertThatNullPointerException().isThrownBy(() -> registration(this.response).build());
 	}
 
 	@Test