How to write the id of the Android item you are creating to the Firebase database

I use the Realtime DataBase. Java.
The problem is that I can't get the created ID. I have a user who creates an order:

The created order is entered in the database

It includes information, the sender's ID, and must also have its own ID shown in the screenshot, which is what I have a problem with.

Order creation code below

    private EditText mDateField, mModelField, mProblemField, mAdressField;
private Button mConfirm;
private FirebaseUser fuser;
@Override     
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
mDateField = findViewById(R.id.date);
mModelField = findViewById(R.id.model);
mProblemField= findViewById(R.id.problem_desc);
mAdressField = findViewById(R.id.adress);
mConfirm = findViewById(R.id.confirm);
fuser = FirebaseAuth.getInstance().getCurrentUser();
final String userID = fuser.getUid();
final String orderid = "";
mConfirm.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String date = mDateField.getText().toString();
String model = mModelField.getText().toString();
String adress = mAdressField.getText().toString();
String problem = mProblemField.getText().toString();
saveOrderInformation(orderid,userID,date,model,adress,problem);
finish();
AppUtilities.showToast(OrderActivity.this,"Order");
}
});
}
private void  saveOrderInformation(String id, String sender, String date, String model, String adress, String problem){
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
HashMap<String,Object> hashMap = new HashMap<>();
hashMap.put("id",id);
hashMap.put("sender",sender);
hashMap.put("date",date);
hashMap.put("model",model);
hashMap.put("adress",adress);
hashMap.put("problem",problem);
reference.child("Orders").push().setValue(hashMap);
}
}

If you want the push() to be also the value of the attribute id, then you can try the following:

private void  saveOrderInformation(String id, String sender, String date, String model, String adress, String problem){
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
String key = reference.child("Orders").push().getKey();
HashMap<String,Object> hashMap = new HashMap<>();
hashMap.put("id",key);
hashMap.put("sender",sender);
hashMap.put("date",date);
hashMap.put("model",model);
hashMap.put("adress",adress);
hashMap.put("problem",problem);
reference.child("Orders").child(key).setValue(hashMap);  
}

You can get the push() value using getKey() and then you can assign it to id and use it as reference when setting the value.

id is blank because you've set it to blank on final String orderid = "";
Either, you can delete that line or you can remove the sender column in the database and set it to id.
Or if you want to set the orderID as id in the database. Then use the below function to obtain the id

DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Orders");
String id = reference.push().getKey();

and set this id to id in the database by

    HashMap<String,Object> hashMap = new HashMap<>();
hashMap.put("id",id);
hashMap.put("sender",sender);
hashMap.put("date",date);
hashMap.put("model",model);
hashMap.put("adress",adress);
hashMap.put("problem",problem);

and then insert the entire dataset into the database by

reference.child(id).setValue(hashMap);