function getPredicate(oContext) {
				var sPredicate = _Helper.getPrivateAnnotation(oContext.getValue(), "predicate");

				if (!sPredicate) {
					bMissingPredicate = true;
				}
				return sPredicate;
			}
Returns the list of predicates corresponding to the given list of contexts, or
<code>null</code if at least one predicate is missing.

@param {sap.ui.model.odata.v4.Context[]} aContexts - A list of contexts
@returns {string[]|null} The corresponding list of predicates

@public