Motivation:

The current implementation still has two problems:

1. The handling of auto-read and self-triggered channelReadComplete events is hidden inside helper methods, making the control flow harder to follow and reason about.
2. When auto-read is enabled, FlowControlHandler should behave as if it is not present in the pipeline. However, the current implementation violates this contract:

   1. read() does not always delegate to ctx.read() when auto-read is enabled.
   2. channelReadComplete() does not always propagate channelReadComplete when auto-read is enabled.
   3. When all reads are satisfied, FlowControlHandler may self-fire channelReadComplete even though it needs to wait for upstream firing channelReadComplete when auto-read is enabled.

Modification:

1. Moved auto-read handling into the top-level control flow, making case-handling explicit.
2. Fixed all cases where FlowControlHandler deviated from transparent behavior when auto-read is enabled.

Result:

1. With auto-read enabled, FlowControlHandler now behaves transparently and preserves the expected channelReadComplete propagation semantics.
2. The control flow is easier to understand and reason about.