public void replaceExternalDataType(ExternalLocation resultExternalLocation,
			ExternalLocation fromExternalLocation, TaskMonitor monitor) throws CancelledException {
		monitor.checkCancelled();
		if (fromExternalLocation != null && resultExternalLocation != null) {
			DataType fromDataTypeForResult = getResultDataType(fromExternalLocation);
			DataType resultDataType = resultExternalLocation.getDataType();
			if (isSameDataType(fromDataTypeForResult, resultDataType)) {
				return; // Already the same.
			}
			resultExternalLocation.setDataType(fromDataTypeForResult);
		}
	}
<CODE>replaceExternalDataType</CODE> replaces the data type of the
external label in program1 with the data type of the external label in program2
at the specified external space address.
@param resultExternalLocation
@param fromExternalLocation
@param monitor the task monitor for notifying the user of this merge's progress.
@throws CancelledException
Ghidra/Features/Base/src/main/java/ghidra/app/merge/listing/ExternalFunctionMerger.java