core/src/main/java/org/nanohttpd/protocols/http/HTTPSession.java
public long getBodySize() {
        if (this.headers.containsKey("content-length")) {
            return Long.parseLong(this.headers.get("content-length"));
        } else if (this.splitbyte < this.rlen) {
            return this.rlen - this.splitbyte;
        }
        return 0;
    }
public long getBodySize() {
        if (this.headers.containsKey("content-length")) {
            return Long.parseLong(this.headers.get("content-length"));
        } else if (this.splitbyte < this.rlen) {
            return this.rlen - this.splitbyte;
        }
        return 0;
    }
Deduce body length in bytes. Either from "content-length" header or read
bytes.