A DESCRIPTION OF THE PROBLEM :
Code runs fine within Eclipse using ECJ but does not compile under javac. When using X2 different from X1, the compiler cannot assign it correctly to the second exception type

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the class, run test phase

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Test should pass
ACTUAL -
Compilation error on line 47

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import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertThrowsExactly;

import java.io.IOException;
import java.util.function.Supplier;

import org.junit.jupiter.api.Test;

public class MinimalTest {

public <T> T supply(Supplier<T> supplier) {
return supplier.get();
}

public @FunctionalInterface interface BadSupplier1<X1 extends Exception, T> {
T get() throws X1;
}

public <X1 extends Exception, T> T supply(Class<X1> x1, BadSupplier1<X1, T> supplier) throws X1 {
return supplier.get();
}

public @FunctionalInterface interface BadSupplier2<X1 extends Exception, X2 extends Exception, T> {
T get() throws X1, X2;
}

public <X1 extends Exception, X2 extends Exception, T> T supply(Class<X1> x1, Class<X2> x2, BadSupplier2<X1, X2, T> supplier) throws X1, X2 {
return supplier.get();
}

public @Test void test() {
assertDoesNotThrow(() -> supply(() -> null));
assertThrowsExactly(IOException.class, () -> supply(IOException.class, () -> {
throw new IOException("To be expected");
}));
assertThrowsExactly(ClassNotFoundException.class, () -> supply(ClassNotFoundException.class, () -> {
throw new ClassNotFoundException("To be expected");
}));
assertThrowsExactly(IOException.class, () -> supply(IOException.class, IOException.class, () -> {
throw new IOException("To be expected");
}));
assertThrowsExactly(ClassNotFoundException.class, () -> supply(ClassNotFoundException.class, ClassNotFoundException.class, () -> {
throw new ClassNotFoundException("To be expected");
}));
// BREAKS ON NEXT LINE in javac but compiles and runs fine with ecj
assertThrowsExactly(IOException.class, () -> supply(IOException.class, ClassNotFoundException.class, () -> {
throw new IOException("To be expected");
}));
}
}

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