src/main/java/org/fest/assertions/GenericAssert.java
public final @NotNull S isNot(@NotNull Condition<A> condition) {
    if (!matches(condition)) {
      return myself();
    }
    failIfCustomMessageIsSet();
    throw failure(errorMessageIfIs(condition));
  }
public final @NotNull S isNot(@NotNull Condition<A> condition) {
    if (!matches(condition)) {
      return myself();
    }
    failIfCustomMessageIsSet();
    throw failure(errorMessageIfIs(condition));
  }
Alias for {@link #doesNotSatisfy(Condition)}.

@param condition the given condition.
@return this assertion object.
@throws NullPointerException if the given condition is {@code null}.
@throws AssertionError       if the actual value satisfies the given condition.
@since 1.2