more robust resolver gathering from spring context

Author: andreacalia

src/java/org/tensorics/core/starter/TensoricsCoreDefaultConfiguration.java

@@ -16,11 +16,14 @@
 @Configuration
 public class TensoricsCoreDefaultConfiguration {
 
-    @Autowired
+    @Autowired(required=false)
     private List<Resolver<?, ?>> resolvers;
-    
+
     @Bean
     public ResolvingEngine resolvingEngine() {
+        if(resolvers == null) {
+            return ResolvingEngines.defaultEngine();
+        }
         return ResolvingEngines.defaultEngineWithAdditional(resolvers.stream().toArray(Resolver[]::new));
     }