Custom Rule Construction Sonarqube

Hello

I am creating a plugin in SonarQube with custom rules and as my first rule, I want to do a validation on If statements where an alarm is triggered every time a literal String enters as a parameter.

I'm following the example framework that is in software documentation , but I can not find any documentation on possible alternatives in building Rules.

To test, I'm using a code from an Android DIVA screen:

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class HardcodeActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_hardcode);
    }

    public void access(View view) {
        EditText hckey = (EditText) findViewById(R.id.hcKey);

        if (hckey.getText().toString().equals("vendorsecretkey")) { // Noncompliant
            Toast.makeText(this, "Access granted! See you on the other side :)", Toast.LENGTH_SHORT).show();
        }
        else {
            Toast.makeText(this, "Access denied! See you in hell :D", Toast.LENGTH_SHORT).show();
        }
    }
}

Given this, the comparison is being made by my Rule in the following section:

    @Override
  public void visitNode(Tree tree){
    IfStatementTree ifStatement = (IfStatementTree) tree;
    ifStatement.condition().kind();
    if (ifStatement.condition().kind() == (Kind.STRING_LITERAL)){
        reportIssue(ifStatement.ifKeyword(), "Comparação if sendo feita com string literal!");
    }
  }

The problem is occurring due to the factors being used for rule comparison, but I can not find any method or attribute that can help me in this comparison. (I also did not find documentation that explains more about IfStatementTree, the most I found was it ).

Could someone please help me with this question or point me to some content that has more information?

Thanks in advance for your attention!