src/main/java/org/fest/assertions/ComparableAssert.java
public final @NotNull S isLessThanOrEqualTo(@Nullable T other) {
    isNotNull();
    if (actual.compareTo(other) <= 0) {
      return myself();
    }
    failIfCustomMessageIsSet();
    throw failure(unexpectedGreaterThan(actual, other));
  }
public final @NotNull S isLessThanOrEqualTo(@Nullable T other) {
    isNotNull();
    if (actual.compareTo(other) <= 0) {
      return myself();
    }
    failIfCustomMessageIsSet();
    throw failure(unexpectedGreaterThan(actual, other));
  }
Verifies that the actual {@link Comparable} is less than or equal to the given one.

@param other the given value.
@return this assertion object.
@throws AssertionError if the actual {@code Comparable} is {@code null}.
@throws AssertionError if the actual {@code Comparable} is not less than or equal to the given one.