@Nullable
public static PsiType getLeastUpperBoundNullable(
@NotNull Iterable<PsiType> collection, @NotNull PsiManager manager) {
Iterator<PsiType> iterator = collection.iterator();
if (!iterator.hasNext()) return null;
PsiType result = iterator.next();
while (iterator.hasNext()) {
result = getLeastUpperBoundNullable(result, iterator.next(), manager);
}
return result;
}
private boolean hasTypeParametersToInfer(PsiClassType classType) {
final PsiClassType.ClassResolveResult resolveResult = classType.resolveGenerics();
PsiClass aClass = resolveResult.getElement();
if (aClass == null) return false;
final Iterable<PsiTypeParameter> iterable =
com.intellij.psi.util.PsiUtil.typeParametersIterable(aClass);
if (!iterable.iterator().hasNext()) {
return false;
}
for (PsiTypeParameter parameter : iterable) {
PsiType type = resolveResult.getSubstitutor().substitute(parameter);
if (type != null) {
if (!(type instanceof PsiWildcardType)
|| ((PsiWildcardType) type).getBound() != null) {
return false;
}
}
}
return true;
}