Created Following DMN via Editor:

Saved it and removed the DMNDI from the XML

opening it again causes following behaviour:

Trying to validate this DMN causes an error, because the decision Service has no attached output decision.

XML looks like this: 

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<dmn:definitions xmlns:dmn="http://www.omg.org/spec/DMN/20180521/MODEL/" xmlns="https://kiegroup.org/dmn/_C737311F-4017-4D97-9D90-636350BAA1B0" xmlns:dc="http://www.omg.org/spec/DMN/20180521/DC/" xmlns:di="http://www.omg.org/spec/DMN/20180521/DI/" xmlns:dmndi="http://www.omg.org/spec/DMN/20180521/DMNDI/" xmlns:feel="http://www.omg.org/spec/DMN/20180521/FEEL/" xmlns:kie="http://www.drools.org/kie/dmn/1.2" expressionLanguage="http://www.omg.org/spec/DMN/20180521/FEEL/" id="_0D65B8E9-DC77-40D2-812E-955C78C88490" name="myName" namespace="https://kiegroup.org/dmn/_C737311F-4017-4D97-9D90-636350BAA1B0" typeLanguage="http://www.omg.org/spec/DMN/20180521/FEEL/">

<dmn:extensionElements/>

<dmn:decisionService id="_65088B96-9A7A-48D4-88A8-2786C28AE6D5" name="DecisionService-1">

<dmn:extensionElements/>

<dmn:variable id="_017846E2-1329-4B3B-A88A-4DE051B53508" name="DecisionService-1"/>

<dmn:outputDecision href="#_27823377-08EF-406E-9DEB-68605AA4D490"/>

<dmn:inputData href="#_6C9ADB85-B512-4953-8281-9B877B09F092"/>

</dmn:decisionService>

<dmn:decision id="_27823377-08EF-406E-9DEB-68605AA4D490" name="Decision-1">

<dmn:extensionElements/>

<dmn:variable id="_832ECAF7-13DD-4D59-96D9-8D13411FABF8" name="Decision-1"/>

<dmn:informationRequirement id="_29B0B949-4C24-4A66-8D28-B32CCB9C297C">

<dmn:requiredInput href="#_6C9ADB85-B512-4953-8281-9B877B09F092"/>

</dmn:informationRequirement>

</dmn:decision>

<dmn:inputData id="_6C9ADB85-B512-4953-8281-9B877B09F092" name="InputData-1">

<dmn:extensionElements/>

<dmn:variable id="_6BF9CCE2-AEB2-4254-AC66-3835DF7C38E7" name="InputData-1"/>

</dmn:inputData>
</dmn:definitions>