message: Fix app crash on sending credential request
diff: @@ -44,11 +44,11 @@ public class CredentialApi extends VcxJava.API {
  }
  private static Callback vcxCredentialSendRequestCB = new Callback() {
  - public void callback(int command_handle,int err, String credential){
  + public void callback(int command_handle, int err) {
  CompletableFuture<String> future = (CompletableFuture<String>) removeFuture(command_handle);
  if (!checkCallback(future,err)) return;
  - String result = credential;
  - future.complete(result);
  + // returning empty string from here because we don't want to complete future with null
  + future.complete("");
  }
  };
  