improve service binding logic

Author: Jonas-Isr

core/src/main/java/com/sap/ai/sdk/core/AiCoreServiceKeyAccessor.java

@@ -81,6 +81,11 @@ static ServiceBinding createServiceBinding(@Nonnull final String serviceKey)
           new AiCoreCredentialsInvalidException("Missing clientid in service key"));
     }
 
+    if (credentials.get("clientsecret") != null && credentials.get("credentials-type") == null) {
+      // add missing "credential-type: binding-secret"
+      credentials.put("credential-type", "binding-secret");
+    }
+
     return new DefaultServiceBindingBuilder()
         .withServiceIdentifier(ServiceIdentifier.AI_CORE)
         .withCredentials(credentials)

core/src/test/java/com/sap/ai/sdk/core/DestinationResolverTest.java

@@ -30,6 +30,9 @@ void testGetDestinationFromBinding() {
     var binding = AiCoreServiceKeyAccessor.createServiceBinding(serviceKey);
     var resolver = new DestinationResolver(() -> List.of(binding));
     var result = resolver.getDestination();
+    assertThat(binding.getCredentials().containsKey("credential-type"))
+        .describedAs("The missing 'credential-type' should have automatically been added")
+        .isTrue();
     assertThat(result.getUri())
         .describedAs("The destination should already contain the /v2 base path")
         .hasToString("https://api.ai.core/v2/");