function onSubmit() {
			oRequestLock = that.oRequestor.lockGroup(sGroupId, that, true);
		}
Returns a promise to be resolved with an OData object for a POST request with the given data.
Calculates the key predicates for all entities in the result before the promise is resolved.

@param {sap.ui.model.odata.v4.lib._GroupLock} oGroupLock
  A lock for the ID of the group that is associated with the request;
  see {@link sap.ui.model.odata.v4.lib._Requestor#request} for details
@param {object} [oData]
  A copy of the data to be sent with the POST request; may be used to tunnel a different
  HTTP method via a property "X-HTTP-Method" (which is removed)
@param {object} [oEntity]
  The entity which contains the ETag to be sent as "If-Match" header with the POST request.
@param {boolean} [bIgnoreETag]
  Whether the entity's ETag should be actively ignored (If-Match:*); used only in case no
  entity is given or an ETag is present
@param {function} [fnOnStrictHandlingFailed]
  If this callback is given, then the preference "handling=strict" is applied.
  If the request fails with an error having <code>oError.strictHandlingFailed</code> set,
  this error is passed to the callback which returns a promise. If this promise resolves with
  <code>true</code> the action is repeated w/o the preference, otherwise this function's
  result promise is rejected with an <code>Error</code> instance <code>oError</code> where
  <code>oError.canceled === true</code>.
@param {function(object):string} [fnGetOriginalResourcePath]
  A function returning the cache's original resource path to be used to build the target path
  for bound messages; it is called once with the response object as parameter
@returns {sap.ui.base.SyncPromise}
  A promise to be resolved with the result of the request.
@throws {Error}
  If the cache does not allow POST, another POST is still being processed, or the cache is
  shared

@public