public Object apply(final Object a, final Object b) {
            if (null == a || null == b) {
                if (null == a && null == b)
                    return null;
                else
                    return null == b ? a : b;
            }
            return ((boolean) a) || ((boolean) b);
        }
Applies "or" to boolean values.

<pre>
    a = true, b = null -> true
    a = false, b = null -> false
    a = null, b = true -> true
    a = null, b = false -> false
    a = null, b = null -> null
</pre>

@since 3.2.0-incubating
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/Operator.java