void visitFrameEnd() {
        if (previousFrame != null) {
            if (stackMapTableEntries == null) {
                stackMapTableEntries = new ByteVector(2048);
            }
            putFrame();
            ++stackMapTableNumberOfEntries;
        }
        previousFrame = currentFrame;
        currentFrame = null;
    }
Ends the visit of {@link #currentFrame} by writing it in the StackMapTable entries and by
updating the StackMapTable number_of_entries (except if the current frame is the first one,
which is implicit in StackMapTable). Then resets {@link #currentFrame} to {@literal null}.
core/src/main/java/com/alibaba/fastjson2/internal/asm/MethodWriter.java