Merge pull request #1411 from microsoftgraph/bugfix/null-allowed-hosts

- fixes a bug where a null collection for allowed hosts would fail client initialization

Author: baywet

src/main/java/com/microsoft/graph/core/authentication/AzureIdentityAccessTokenProvider.java

@@ -22,7 +22,7 @@ public AzureIdentityAccessTokenProvider(@Nonnull TokenCredential tokenCredential
     public AzureIdentityAccessTokenProvider(@Nonnull final TokenCredential tokenCredential, @Nonnull final String[] allowedHosts,
             @Nullable final ObservabilityOptions observabilityOptions, @Nonnull final String... scopes) {
         super(tokenCredential, allowedHosts, observabilityOptions, scopes);
-        if (allowedHosts.length == 0) {
+        if (allowedHosts == null || allowedHosts.length == 0) {
             final HashSet<String> allowedHostsSet = new HashSet<String>();
             allowedHostsSet.add("graph.microsoft.com");
             allowedHostsSet.add("graph.microsoft.us");