cloud_firestore plugin error about class R

[CanbinMei]

When I try to launch the app, this happens.
Anyone know what is going on?
I am trying to use Firebase core, auth and cloud firestore with my flutter app.

Launching lib/main.dart on sdk gphone x86 in debug mode...
Running Gradle task 'assembleDebug'...

3.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
2.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
2.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
2.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
2.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
3.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
3.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
3.java:9: error: class R is public, should be declared in a file named R.java
public final class R {
^
3.java:10: error: class R is public, should be declared in a file named R.java
public final class R {
^
9 errors

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':app:compileDebugJavaWithJavac'.

Compilation failed; see the compiler error output for details.

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 5s
The built failed likely due to AndroidX incompatibilities in a plugin. The tool is about to try using Jetfier to solve the incompatibility.
Running Gradle task 'assembleAarRelease'...
Building plugin cloud_firestore...
Exception: The plugin cloud_firestore could not be built due to the issue above.