import java.util.List; class Sample { <T extends List<K>, K extends List<T>> T foo(){ <error descr="Incompatible types. Found: 'K', required: 'T'">T t = foo().get(0);</error> <error descr="Incompatible types. Found: 'K', required: 'K'">K k = foo().get(0);</error> <error descr="Incompatible types. Found: 'T', required: 'T'">T t1 = foo().get(0).get(0);</error> String s = foo(); <error descr="Incompatible types. Found: 'K', required: 'java.lang.String'">String s1 = foo().get(0);</error> return null; } { foo(); } }