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Client Versioning

<p>
	Client version headers are used to support backwards compatibility for breaking REST interface changes.
	Using them, you're able to return different responses based on which client is making a request.
</p>
<p>
	The APIs involved with defining client version headers are:
</p>
<ul class='javatree'>
	<li class='ja'>{@link oajr.annotation.Rest#clientVersionHeader() Rest(clientVersionHeader)}
	<li class='jm'>{@link oajr.RestContextBuilder#clientVersionHeader(String)}
	<li class='ja'>{@link oajr.annotation.RestMethod#clientVersion() RestMethod(clientVersion)}
</ul>
<h5 class='figure'>Example:</h5>
<p class='bpcode w800'>
	<jc>// Option #1 - Defined via annotation resolving to a config file setting with default value.</jc>
	<ja>@Rest</ja>(clientVersionHeader=<js>"Client-Version"</js>)
	<jk>public class</jk> MyResource {

		<jc>// Call this method if Client-Version is at least 2.0.
		// Note that this also matches 2.0.1.</jc>
		<ja>@RestMethod</ja>(name=<jsf>GET</jsf>, path=<js>"/foobar"</js>, clientVersion=<js>"2.0"</js>)
		<jk>public</jk> Object method1() {
			...
		}
	
		<jc>// Call this method if Client-Version is at least 1.1, but less than 2.0.</jc>
		<ja>@RestMethod</ja>(name=<jsf>GET</jsf>, path=<js>"/foobar"</js>, clientVersion=<js>"[1.1,2.0)"</js>)
		<jk>public</jk> Object method2() {
			...
		}
	
		<jc>// Call this method if Client-Version is less than 1.1.</jc>
		<ja>@RestMethod</ja>(name=<jsf>GET</jsf>, path=<js>"/foobar"</js>, clientVersion=<js>"[0,1.1)"</js>)
		<jk>public</jk> Object method3() {
			...
		}
</p>

<ul class='seealso'>
	<li class='jf'>{@link oajr.RestContext#REST_clientVersionHeader}
</ul>