Update IllegalArgumentExceptionMessages.java

fix typo

Author: mattmazzola

src/main/java/com/microsoft/aad/msal4j/IllegalArgumentExceptionMessages.java

@@ -7,7 +7,7 @@ class IllegalArgumentExceptionMessages {
 
     final static String AUTHORITY_URI_EMPTY_PATH_SEGMENT = "Authority Uri should not have empty path segments";
 
-    final static String AUTHORITY_URI_MISSING_PATH_SEGMENT = "Authority Uri must have a least one path segment. This is usually 'common' or the application's tenant id.";
+    final static String AUTHORITY_URI_MISSING_PATH_SEGMENT = "Authority Uri must have at least one path segment. This is usually 'common' or the application's tenant id.";
 
     final static String AUTHORITY_URI_EMPTY_PATH = "Authority Uri should have at least one segment in the path";