private boolean hasContentLength() {
        return expectedContentLength != UNSET_CONTENT_LENGTH;
    }
This checks that the content length does what it says, preventing a client from causing Zuul to misinterpret the
request.  Because this class is meant to work in an HTTP/2 setting, the content length and transfer encoding
checks are more semantics.  In particular, this checks:
<ul>
    <li>No duplicate Content length</li>
    <li>Content Length (if present) must always be greater than or equal to how much content has been seen</li>
    <li>Content Length (if present) must always be equal to how much content has been seen by the end</li>
    <li>Content Length cannot be present along with chunked transfer encoding.</li>
</ul>
zuul-core/src/main/java/com/netflix/zuul/netty/server/http2/Http2ContentLengthEnforcingHandler.java