ADDITIONAL SYSTEM INFORMATION :
openjdk 22.0.1 2024-04-16
OpenJDK Runtime Environment GraalVM CE 22.0.1+8.1 (build 22.0.1+8-jvmci-b01)
OpenJDK 64-Bit Server VM GraalVM CE 22.0.1+8.1 (build 22.0.1+8-jvmci-b01, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
Compiler picks inapplicable `UnaryOperator` overload instead of `Function` one:

```
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.function.UnaryOperator;

public class Main<T> {
    String map(UnaryOperator<T> mapper) {
        return "op";
    }

    <R> String map(Function<T, R> mapper) {
        return "fn";
    }
    
    public static void main(String args[]) {
      new Main<Integer>().map(i -> "");
    }
}
```

Compiler picks the `UnaryOperator` method and gives error:
```
error: incompatible types: bad return type in lambda expression
      new Main<Integer>().map(i -> "");
                                   ^
    String cannot be converted to Integer
```

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Compiler pick the correct applicable overload and code compiles
ACTUAL -
Compilation failure

---------- BEGIN SOURCE ----------
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.function.UnaryOperator;

public class Main<T> {
    String map(UnaryOperator<T> mapper) {
        return "op";
    }

    <R> String map(Function<T, R> mapper) {
        return "fn";
    }
    
    public static void main(String args[]) {
      new Main<Integer>().map(i -> "");
    }
}
---------- END SOURCE ----------