rest-assured/src/main/java/io/restassured/http/Cookies.java
public String getValue(String cookieName) {
        AssertParameter.notNull(cookieName, "Cookie name");
        return cookies.getValue(cookieName);
    }
public String getValue(String cookieName) {
        AssertParameter.notNull(cookieName, "Cookie name");
        return cookies.getValue(cookieName);
    }
Get a single cookie <i>value</i> with the supplied name. If there are several cookies matching the <code>cookieName</code> then
the first one is returned.

@param cookieName The name of the cookie to find
@return The found cookie or <code>null</code> if no cookie was found.