Merge AbstractBufferedEncoder base class into its only subclass OutputStreamEncoder.

After the prior cleanup, this is the last use of the base class left and we are unlikely to reuse the base class for another different type, so we can merge it in.

PiperOrigin-RevId: 848198069

Author: protobuf-github-bot

java/core/src/main/java/com/google/protobuf/CodedOutputStream.java

@@ -1682,14 +1682,28 @@ private void encode(String value) throws IOException {
     }
   }
 
-  /** Abstract base class for buffered encoders. */
-  private abstract static class AbstractBufferedEncoder extends CodedOutputStream {
-    final byte[] buffer;
-    final int limit;
-    int position;
-    int totalBytesWritten;
-
-    AbstractBufferedEncoder(int bufferSize) {
+  /**
+   * An encoder that writes into an OutputStream. This internally uses an array for buffering to
+   * improve efficiency.
+   */
+  private static final class OutputStreamEncoder extends CodedOutputStream {
+    private final byte[] buffer;
+    private final int limit;
+    private int position;
+    private int totalBytesWritten;
+
+    /**
+     * An {@link CodedOutputStream} that decorates an {@link OutputStream}. It performs internal
+     * buffering to optimize writes to the {@link OutputStream}.
+     */
+    private final OutputStream out;
+
+    OutputStreamEncoder(OutputStream out, int bufferSize) {
+      if (out == null) {
+        throw new NullPointerException("out");
+      }
+      this.out = out;
+
       if (bufferSize < 0) {
         throw new IllegalArgumentException("bufferSize must be >= 0");
       }
@@ -1843,22 +1857,6 @@ final void bufferFixed64NoTag(long value) {
       this.position = position;
       totalBytesWritten += FIXED64_SIZE;
     }
-  }
-
-  /**
-   * An {@link CodedOutputStream} that decorates an {@link OutputStream}. It performs internal
-   * buffering to optimize writes to the {@link OutputStream}.
-   */
-  private static final class OutputStreamEncoder extends AbstractBufferedEncoder {
-    private final OutputStream out;
-
-    OutputStreamEncoder(OutputStream out, int bufferSize) {
-      super(bufferSize);
-      if (out == null) {
-        throw new NullPointerException("out");
-      }
-      this.out = out;
-    }
 
     @Override
     public void writeTag(final int fieldNumber, final int wireType) throws IOException {