code: public static Type[] getImplicitLowerBounds(final WildcardType wildcardType) {
          Validate.notNull(wildcardType, "wildcardType is null");
          final Type[] bounds = wildcardType.getLowerBounds();
  
          return bounds.length == 0 ? new Type[] { null } : bounds;
      }
docs: <p>Returns an array containing a single value of {@code null} if
  {@link WildcardType#getLowerBounds()} returns an empty array. Otherwise,
  it returns the result of {@link WildcardType#getLowerBounds()}.</p>
  
  @param wildcardType the subject wildcard type, not {@code null}
  @return a non-empty array containing the lower bounds of the wildcard
  type.