Rename InputStreamSubscriber to SubscriberInputStream

It is both, but InputStream is what's exposed for public use,
in effect an InputStream backed by a Subscriber source.

See gh-31677

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferUtils.java

@@ -472,16 +472,16 @@ public abstract class DataBufferUtils {
 	 * Note: {@link Subscription#request(long)} happens eagerly for the first time upon subscription
 	 * and then repeats every time {@code bufferSize - (bufferSize >> 2)} consumed.
 	 * @param publisher the source of {@link DataBuffer} which should be represented as an {@link InputStream}
-	 * @param bufferSize the maximum amount of {@link DataBuffer} prefetched in advance and stored inside {@link InputStream}
+	 * @param demand the maximum number of buffers to request from the Publisher and buffer on an ongoing basis
 	 * @return an {@link InputStream} instance representing given {@link Publisher} messages
 	 */
-	public static <T extends DataBuffer> InputStream subscribeAsInputStream(Publisher<T> publisher, int bufferSize) {
+	public static <T extends DataBuffer> InputStream subscriberInputStream(Publisher<T> publisher, int demand) {
 		Assert.notNull(publisher, "Publisher must not be null");
-		Assert.isTrue(bufferSize > 0, "Buffer size must be > 0");
+		Assert.isTrue(demand > 0, "maxBufferCount must be > 0");
 
-		InputStreamSubscriber inputStreamSubscriber = new InputStreamSubscriber(bufferSize);
-		publisher.subscribe(inputStreamSubscriber);
-		return inputStreamSubscriber;
+		SubscriberInputStream subscriber = new SubscriberInputStream(demand);
+		publisher.subscribe(subscriber);
+		return subscriber;
 	}
 
 

spring-core/src/main/java/org/springframework/core/io/buffer/SubscriberInputStream.java

@@ -39,13 +39,13 @@ import org.springframework.util.Assert;
  * Bridges between {@link Publisher Publisher<DataBuffer>} and {@link InputStream}.
  *
  * <p>Note that this class has a near duplicate in
- * {@link org.springframework.http.client.InputStreamSubscriber}.
+ * {@link org.springframework.http.client.SubscriberInputStream}.
  *
  * @author Oleh Dokuka
  * @author Rossen Stoyanchev
  * @since 6.2
  */
-final class InputStreamSubscriber extends InputStream implements Subscriber<DataBuffer> {
+final class SubscriberInputStream extends InputStream implements Subscriber<DataBuffer> {
 
 	private static final Object READY = new Object();
 
@@ -82,10 +82,10 @@ final class InputStreamSubscriber extends InputStream implements Subscriber<Data
 	private Throwable error;
 
 
-	InputStreamSubscriber(int prefetch) {
-		this.prefetch = prefetch;
-		this.limit = (prefetch == Integer.MAX_VALUE ? Integer.MAX_VALUE : prefetch - (prefetch >> 2));
-		this.queue = new ArrayBlockingQueue<>(prefetch);
+	SubscriberInputStream(int demand) {
+		this.prefetch = demand;
+		this.limit = (demand == Integer.MAX_VALUE ? Integer.MAX_VALUE : demand - (demand >> 2));
+		this.queue = new ArrayBlockingQueue<>(demand);
 		this.lock = new ReentrantLock(false);
 	}