@Override
            public boolean requiresAggregation() {
                if (ResponseAs.this.requiresAggregation()) {
                    // The response was aggregated already.
                    return true;
                }
                return after.requiresAggregation();
            }
Returns a composed {@link ResponseAs} that first applies this {@link ResponseAs} to
its input, and then applies the {@code after} {@link ResponseAs} to the result.
core/src/main/java/com/linecorp/armeria/client/ResponseAs.java