public @NotNull Self withFirstNonWhitespaceChild(final @NotNull ElementPattern<? extends PsiElement> pattern) {
    return withChildren(collection(PsiElement.class).filter(not(psiElement().whitespace()), collection(PsiElement.class).first(pattern)));
  }
public @NotNull Self withFirstNonWhitespaceChild(final @NotNull ElementPattern<? extends PsiElement> pattern)