src/main/java/io/reactivex/processors/ReplayProcessor.java
@CheckReturnValue
    @NonNull
    public static <T> ReplayProcessor<T> create(int capacityHint) {
        return new ReplayProcessor<T>(new UnboundedReplayBuffer<T>(capacityHint));
    }
@CheckReturnValue
    @NonNull
    public static <T> ReplayProcessor<T> create(int capacityHint) {
        return new ReplayProcessor<T>(new UnboundedReplayBuffer<T>(capacityHint));
    }
Creates an unbounded ReplayProcessor with the specified initial buffer capacity.
<p>
Use this method to avoid excessive array reallocation while the internal buffer grows to accommodate new
items. For example, if you know that the buffer will hold 32k items, you can ask the
{@code ReplayProcessor} to preallocate its internal array with a capacity to hold that many items. Once
the items start to arrive, the internal array won't need to grow, creating less garbage and no overhead
due to frequent array-copying.

@param <T>
the type of items observed and emitted by this type of processor
@param capacityHint
the initial buffer capacity
@return the created processor