Flutter Issue - source value 8 is obsolete and will be removed in a future release

warning: [options] source value 8 is obsolete and will be removed in a future release
warning: [options] target value 8 is obsolete and will be removed in a future release
warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.

Add this code to your build.gradle:

android/build.gradle

allprojects {
  repositories {
    google()
    mavenCentral()
  }
  tasks.withType(JavaCompile) {
    options.compilerArgs << '-Xlint:-options'
  }
}