SAPUI5 the built-in AJAX class library handles post requests without committing HTTP HEADERS

SAPUI5 the built-in Ajax class library, ignoring the HTTP headers when submitting a POST request. The GET request does not have this problem.

The following code cannot commit HTTP Headers

sURL = Getsmpurl () + "/odata/applications/latest/com.sap.flight.kapsel/connections";
$.ajax ({
    type: "POST",
    Cache:false,
    url:surl,
    data:payload,
    beforesend:function (Request) { C6/>request.setrequestheader (' Content-type ', "application/xml");
    },
    success:function (data, ajaxoptions, XHR) {
        alert ("Passed register")
    ,
    error:function (XHR, ajaxoptions, thrownerror) {
        alert ("Shit") );
    },
    xhrfields: {
        withcredentials:true,
    }
});

The following code can commit HTTP Headers

Write code here
sURL = Getsmpurl () + "/odata/applications/latest/com.sap.flight.kapsel";
$.ajax ({
Headers: {
' Authorization ': "Basic" + Btoa (GetUserName () + ":" + GetPassword ())
},
Type: "GET",
Cache:false,
Url:surl,
DataType: ' xml ',
Beforesend:function (Request) {

    },
    success:function (data, ajaxoptions, XHR) {
        alert ("Passed authentication");
    },
    error:function ( XHR, Ajaxoptions, thrownerror) {
        alert ("shit");
    },
    xhrfields: {
        withcredentials:true,
    }
} );

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