Why is setting the screen lock type by EMDK "DevAdmin" profile not supported on TC75?

We want to programmatically change the screen lock type at run time to avoid doing this manually or by an ADB script during staging.

Unfortunately this doesn't seem to be supported on TC75 with Android 5.1.1 (with EMDK service version 6.0.7.307 and MX framework version 6.1.0.9).

The profile parameter string we use for setting the screen lock type looks like this (with "lockType" set to 5):

 

profileParamString[0]=

   "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
   +"<characteristic type=\"Profile\">"
   +"<parm name=\"ProfileName\" value=\""+profileName+"\"/>"
   // +"<parm name=\"TargetSystemVersion\" value=\"6.1\"/>"
   +"<characteristic type=\"DevAdmin\" version=\"6.0\">"
   +"<parm name=\"ScreenLockType\" value=\""+lockType+"\" />"
   +"</characteristic>"
   +"</characteristic>";

 

But the call is not successful and in the log cat I see these messages:

 

02-02 16:46:14.691 3141-3155/? D/com.symbol.emdk.emdkservice.ProfileHandler: createProfile - mxProfile = <?xml version="1.0" encoding="UTF-8"?><wap-provisioningdoc><characteristic type="DevAdmin" version="6.0"><parm name="ScreenLockType" value="5"/></characteristic></wap-provisioningdoc>

02-02 16:46:14.698 2665-3274/? I/MxFrameworkService: processXmlRequest: call AIDL getValue() on: DevAdmin

02-02 16:46:14.700 2665-3274/? I/MxFrameworkService: processXmlRequest: AIDL getValue(): return value = null

02-02 16:46:14.713 5124-5124/? I/MxStatsCSPService: onServiceConnected

02-02 16:46:14.728 3141-3155/? D/com.symbol.emdk.emdkservice.ProfileHandler: createProfile - mxResponse = <wap-provisioningdoc><characteristic type="DevAdmin" version="6.0"><parm-error name="ScreenLockType" value="5" desc="This Feature is not supported below OSx6.0 version"/></characteristic></wap-provisioningdoc>

 

Apparently the error description "This Feature is not supported below OSx6.0" is related to the Android OS version, not to the MX version.

What is the reason for this restriction to Android 6 (or higher)?

It is not documented on DevAdmin Manager - Zebra Technologies Techdocs.

 

We need this feature also on TC75, TC70 and TC8000 (which will presumably never get Android 6).