fnChainMetadataLoaded = function() {
				return pMetadataLoaded;
			}
Returns a promise for the loaded state of the metadata.

The metadata needs to be loaded prior to performing OData calls.
Chaining to the returned promise ensures that all required parameters have been loaded, e.g.
the security token, see {@link #getSecurityToken}.

The returned promise depends on the optional parameter <code>bRejectOnFailure</code>.

<code>bRejectOnFailure=false</code>:
The promise won't get rejected in case the metadata or annotation loading failed but is
only resolved if
<ol>
<li>the metadata are loaded successfully,</li>
<li>the annotations are processed, provided the model parameter
<code>loadAnnotationsJoined</code> has been set.</li>
</ol>
Use this promise for delaying OData calls until all required information is available, i.e.
this promise is resolved.

<code>bRejectOnFailure=true</code>:
Since 1.79, the parameter <code>bRejectOnFailure</code> allows to request a promise that is
rejected when one of the following fails:
<ul>
<li>the loading of the metadata,</li>
<li>the loading of the annotations, provided the model parameter
<code>loadAnnotationsJoined</code> has been set.</li>
</ul>
The promise is fulfilled upon successful loading of both. This promise can be used to start
processing OData calls when it is fulfilled and to display an error message when it is
rejected. See also the example below.

If the method <code>refreshMetadata</code> is called after the returned promise is already
resolved or rejected, you should use the promise returned by <code>refreshMetadata</code>
to get information about the refreshed state.

@example
var oModel  = this.oModel, // v2.ODataModel
    that = this;
oModel.metadataLoaded(true).then(
    function () {
        // model is ready now
        oModel.createKey("PERSON", {"ID" : 4711, "TASK_GUID": "myguid"});
    },
    function () {
        // Display error information so that the user knows that the application does not work.
        that.navigateToErrorPage();
    });

@param {boolean} [bRejectOnFailure=false]
  Determines since 1.79 whether the returned promise is rejected when the initial loading
  of the metadata fails. In case the model parameter <code>loadAnnotationsJoined</code> is
  set, the returned promise fails also if loading the annotations fails.

@returns {Promise} A promise on metadata loaded state

@public
@since 1.30