Use filter (for a list) and MicroflowParameterObject
const microflowWithParameters = loadedFlow.objectCollection.objects.filter(element => element instanceof microflows.MicroflowParameterObject)
see this serialized code
var lDAPBaseName1 = microflows.MicroflowParameterObject.create(model);
lDAPBaseName1.relativeMiddlePoint = {"x":100,"y":0};
lDAPBaseName1.size = {"width":30,"height":30};
lDAPBaseName1.name = "LDAPBaseName";
lDAPBaseName1.variableType = objectType1;
microflowObjectCollection1.objects.push(lDAPBaseName1);