test empty = null for settings

src/main/java/stirling/software/SPDF/config/AppConfig.java

@@ -1,5 +1,6 @@
 package stirling.software.SPDF.config;
 
+import org.springframework.beans.PropertyEditorRegistrar;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -8,6 +9,18 @@ import stirling.software.SPDF.model.ApplicationProperties;
 @Configuration
 public class AppConfig {
 
+	@Bean
+    public CustomEditorConfigurer customEditorConfigurer() {
+        return new CustomEditorConfigurer();
+    }
+
+    @Bean
+    public PropertyEditorRegistrar propertyEditorRegistrar() {
+        return registry -> {
+            registry.registerCustomEditor(String.class, new EmptyStringAsNullEditor());
+        };
+    }
+    
     @Autowired
     ApplicationProperties applicationProperties;