@Nullable
  private static PsiType extractComponentType(PsiType type) {
    if (type instanceof PsiArrayType) return ((PsiArrayType)type).getComponentType();
    return PsiUtil.substituteTypeParameter(type, CommonClassNames.JAVA_UTIL_COLLECTION, 0, false);
  }
@Nullable
  private static PsiType extractComponentType(PsiType type)