Merging of nested ifs not always correct

[Luro02]

Summary

For the below code, it seems to suggest merging the nested if with the outer one through &&, even though that is not applicable.

Lint Name

ChainedIfCheck

Reproducer

if (a <= 0) {
    if (a == -3) {
        System.out.println("a is -3");
    }
    return;
}

if (a == 1) {
    if (b == 2) {
        System.out.println("a is 1");
    }
} else if (a == 2) {
    if (b == 3) {
        throw new IllegalStateException("an error occurred");
    }
    System.out.println("a is 2");
} else if (a == 3) {
    if (b == 3) {
        System.out.println("a is 3 and b is 3");
    } else {
        throw new IllegalStateException("should never happen");
    }
}

and

if (a == 2) {
    if (b == 2) {
        throw new IllegalStateException("an error occurred");
    }
    System.out.println("a is 2, b is not 2");
}