Merge pull request #149 from tsurdilo/fixsubflowrefser

fix subflow ref serializer

Author: tsurdilo

api/src/main/java/io/serverlessworkflow/api/serializers/SubFlowRefSerializer.java

@@ -18,7 +18,6 @@
 import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.ser.std.StdSerializer;
-import io.serverlessworkflow.api.functions.FunctionRef;
 import io.serverlessworkflow.api.functions.SubFlowRef;
 import java.io.IOException;
 
@@ -40,7 +39,7 @@ public void serialize(SubFlowRef subflowRef, JsonGenerator gen, SerializerProvid
       if ((subflowRef.getWorkflowId() == null || subflowRef.getWorkflowId().isEmpty())
           && (subflowRef.getVersion() == null || subflowRef.getVersion().isEmpty())
           && (subflowRef.getInvoke() == null
-              || subflowRef.getInvoke().equals(FunctionRef.Invoke.SYNC))) {
+              || subflowRef.getInvoke().equals(SubFlowRef.Invoke.SYNC))) {
         gen.writeString(subflowRef.getWorkflowId());
       } else {
         gen.writeStartObject();