Retrieve Cases associated with Contacts and Accounts in one go

I was working on some work and got a requirement to get Cases of linked with Account and Contact. 

In a normal scenario, we can always do two Calls like 

Cases where CustomerID = Account GUID and Cases where CustomerID = Contact GUID


Somehow, I didn't like this approach of making two calls. Spending sometime helped to reduce a call and I was able to retrieve Cases related to Account and Contact in one call.


Here is the FetchXML I have used and uitype plays a major role here.
           

 

<fetch version='1.0' output-format='xml-platform' mapping='logical' distinct='false'>

                                      <entity name='incident'>

                                        <attribute name='title' />

                                        <attribute name='ticketnumber' />

                                        <attribute name='createdon' />

                                        <attribute name='incidentid' />

                                        <attribute name='caseorigincode' />

                                        <order attribute='title' descending='false' />

                                        <filter type='and'>

                                          <condition attribute='customerid' operator='in'>

                                            <value uitype='account'>{ACCOUNT-GUID}</value>

                                            <value uitype='contact'>{Contact-GUID}</value>

                                          </condition>

                                        </filter>

                                     </entity>

                                    </fetch>