// Issue 1142 https://github.com/typetools/checker-framework/issues/1142 import java.util.concurrent.ConcurrentHashMap; import org.checkerframework.checker.nullness.qual.Nullable; class Issue1142 { void foo() { //:: error: (type.argument.type.incompatible) ConcurrentHashMap<Integer, @Nullable Integer> chm1 = new ConcurrentHashMap<>(); chm1.put(1, null); } }