refactored to make use of the ServiceType enum throughout backend and frontend for typesafety

backend/src/test/java/com/vaessl/app/connection/HomeboxConnectionProviderTest.java

@@ -6,6 +6,7 @@ import org.junit.jupiter.api.Test;
 
 import com.vaessl.app.exception.EmptyCredentialsException;
 import static com.vaessl.app.Mockdata.*;
+import static com.vaessl.app.connection.ServiceType.HOMEBOX;
 import static org.assertj.core.api.Assertions.assertThat;
 
 class HomeboxConnectionProviderTest {
@@ -13,8 +14,9 @@ class HomeboxConnectionProviderTest {
     private final HomeboxConnectionProvider provider = new HomeboxConnectionProvider(null, null);
 
     @Test
-    void checkCredentials_ShouldThrowException_WhenFieldsAreMissing() {
-        ConnectionRequest request = new ConnectionRequest(MOCK_URL, "HOMEBOX", null, null, false);
+    void checkCredentialsShouldThrowExceptionWhenFieldsAreMissing() {
+        ConnectionRequest request =
+                new ConnectionRequest(MOCK_URL, HOMEBOX, null, null, false);
 
         EmptyCredentialsException exception = assertThrows(EmptyCredentialsException.class, () -> {
             provider.checkCredentials(request);