Places a value in this context map under the given key only if the given {@code value} argument is not null.
@param key the attribute key under which the non-null value will be stored
@param value the non-null value to store. If {@code null}, this method does nothing and returns immediately.
Places a value in this context map under the given key only if the given {@code value} argument is not null.
@param key the attribute key under which the non-null value will be stored @param value the non-null value to store. If {@code null}, this method does nothing and returns immediately.