title: Biometric Prompt not showing prompt for face unlock
body: <p>I am trying to authenticate my app with fingerprint as well as face unlock depending upon user has setup authentication for his device.Now in my app I want face unlock which is not getting displayed.For that I have removed finger prints but it never comes up.My device supports Android 10.I know oem select what to show i.e. fingerprint or face prompt.How can i check whether my app supports face unlock.
  Below is my implementation </p>
  
  <pre><code>Gradle :
   implementation "androidx.biometric:biometric:1.0.1"
  
  Code Implementation:
  
  public class MainActivity extends AppCompatActivity {
  
      Button btnHello;
      Executor executor;
      BiometricPrompt.PromptInfo promptInfo;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          executor = ContextCompat.getMainExecutor(this);
          final BiometricPrompt biometricPrompt = new BiometricPrompt(MainActivity.this,
                  executor, new BiometricPrompt.AuthenticationCallback() {
              @Override
              public void onAuthenticationError(int errorCode,
                                                @NonNull CharSequence errString) {
                  super.onAuthenticationError(errorCode, errString);
                  Toast.makeText(getApplicationContext(),
                          "Authentication error: " + errString, Toast.LENGTH_SHORT)
                          .show();
              }
  
              @Override
              public void onAuthenticationSucceeded(
                      @NonNull BiometricPrompt.AuthenticationResult result) {
                  super.onAuthenticationSucceeded(result);
                  Toast.makeText(getApplicationContext(),
                          "Authentication succeeded!", Toast.LENGTH_SHORT).show();
              }
  
              @Override
              public void onAuthenticationFailed() {
                  super.onAuthenticationFailed();
                  Toast.makeText(getApplicationContext(), "Authentication failed",
                          Toast.LENGTH_SHORT)
                          .show();
              }
          });
  
          promptInfo = new BiometricPrompt.PromptInfo.Builder()
                  .setTitle("Biometric login for my app")
                  .setSubtitle("Log in using your biometric credential")
                  .setNegativeButtonText("Use account password")
                  .build();
  
          // Prompt appears when user clicks "Log in".
          // Consider integrating with the keystore to unlock cryptographic operations,
          // if needed by your app.
          Button biometricLoginButton = findViewById(R.id.btnHello);
          biometricLoginButton.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View v) {
                  biometricPrompt.authenticate(promptInfo);
              }
          });
      }
  
  
  
  
  
  
  
  }
  </code></pre>