netty: Removed 4096 min buffer size (#11856)

* netty: Removed 4096 min buffer size

Author: AgraVator

netty/src/main/java/io/grpc/netty/NettyWritableBufferAllocator.java

@@ -33,9 +33,6 @@
  */
 class NettyWritableBufferAllocator implements WritableBufferAllocator {
 
-  // Use 4k as our minimum buffer size.
-  private static final int MIN_BUFFER = 4 * 1024;
-
   // Set the maximum buffer size to 1MB.
   private static final int MAX_BUFFER = 1024 * 1024;
 
@@ -47,7 +44,7 @@ class NettyWritableBufferAllocator implements WritableBufferAllocator {
 
   @Override
   public WritableBuffer allocate(int capacityHint) {
-    capacityHint = Math.min(MAX_BUFFER, Math.max(MIN_BUFFER, capacityHint));
+    capacityHint = Math.min(MAX_BUFFER, capacityHint);
     return new NettyWritableBuffer(allocator.buffer(capacityHint, capacityHint));
   }
 }

netty/src/test/java/io/grpc/netty/NettyWritableBufferAllocatorTest.java

@@ -40,13 +40,6 @@ protected WritableBufferAllocator allocator() {
     return allocator;
   }
 
-  @Test
-  public void testCapacityHasMinimum() {
-    WritableBuffer buffer = allocator().allocate(100);
-    assertEquals(0, buffer.readableBytes());
-    assertEquals(4096, buffer.writableBytes());
-  }
-
   @Test
   public void testCapacityIsExactAboveMinimum() {
     WritableBuffer buffer = allocator().allocate(9000);