I'm wondering if the below code is buggy:

import java.util.*;

public class Test {
    static <K,V> Iterable<Map.Entry<K,V>> getEntries() {return null;}    

    public static void main(String[] args) {
        for (Map.Entry<?,Integer> e : getEntries()) {
        }
    }
}


The compiler reports the following error:

Test.java:7: incompatible types
found   : java.util.Map.Entry<java.lang.Object,java.lang.Object>
required: java.util.Map.Entry<?,java.lang.Integer>
                for (Map.Entry<?,Integer> e : getEntries()) {
                                                        ^

Why isn't the enhanced for loop expression used as a context for applying the
type inference algorithm? Is this a bug or am I expected to explicitly provide an instantiation for
all method parameters?

At first, it seemed that the problem was related to the enhanced for loop expression; so I tried
The following workaround (whichdoesn't compile either):

public class Test {
    static <K,V> Iterable<Map.Entry<K,V>> getEntries() {return null;}    

    public static void main(String[] args) {
        Iterable<Map.Entry<?,Integer>> it = getEntries(); //should be a workaround
        for (Map.Entry<?,Integer> e : it) {
        }
    }
}

But, surprisingly, I found that this code (surprisingly) compiles:

public class Test {
    static <K,V> Iterable<Map.Entry<K,V>> getEntries() {return null;}    

    public static void main(String[] args) {
        Iterable<Map.Entry<String,Integer>> it = getEntries(); //should be a workaround
        for (Map.Entry<?,Integer> e : it) {
        }
    }
}

In other words it seems that the inference process only works with concrete types but not with wildcard types.
Is this problem due to a bug in the inference process?