I have figured this out and have it implemented in my app, TapN.
First get the original clipboard contents, save that, copy to the clipboard your content, then paste it, then copy the original content back.
public void inputData(Context c, String data, AccessibilityNodeInfo source) {
try {
String lastClip = clipboard.getPrimaryClip().getItemAt(0).coerceToText(c)
.toString();
} catch (Exception e) {
lastClip = "";
}
Log.d("THE NODE INFO", source.toString());
ClipData clip = ClipData.newPlainText("nfc_input", data);
clipboard.setPrimaryClip(clip);
Log.d("SENDING DATA", Boolean.toString(source.refresh()));
Log.d("SENDING DATA", Boolean.toString(source
.performAction(AccessibilityNodeInfo.ACTION_PASTE)));
ClipData clip = ClipData.newPlainText("nfc_input", lastClip);
clipboard.setPrimaryClip(clip);
}