Returns {@code true} if this set contains the specified element.
More formally, returns {@code true} if and only if this set
contains an element {@code e} such that
{@code Objects.equals(o, e)}.
@param o element whose presence in this set is to be tested
@return {@code true} if this set contains the specified element
Returns {@code true} if this set contains the specified element. More formally, returns {@code true} if and only if this set contains an element {@code e} such that {@code Objects.equals(o, e)}.
@param o element whose presence in this set is to be tested @return {@code true} if this set contains the specified element