Add unit test assertions to verify the generated token has no padding.

Change-Id: I7b948a13a075d7afeac19f96b9372f23b60d4eda

Author: huangjiahua

cab-token-generator/javatests/com/google/auth/credentialaccessboundary/ClientSideCredentialAccessBoundaryFactoryTest.java

@@ -745,6 +745,9 @@ public void generateToken_withAvailablityCondition_success() throws Exception {
     CabToken cabToken = parseCabToken(token);
     assertEquals("accessToken", cabToken.intermediateToken);
 
+    // Verifies the encrypted restriction has no padding
+    assertFalse(cabToken.encryptedRestriction.contains(String.valueOf("=")));
+
     // Checks the encrypted restriction is the correct proto format of the CredentialAccessBoundary.
     ClientSideAccessBoundary clientSideAccessBoundary =
         decryptRestriction(
@@ -795,6 +798,9 @@ public void generateToken_withoutAvailabilityCondition_success() throws Exceptio
     CabToken cabToken = parseCabToken(token);
     assertEquals("accessToken", cabToken.intermediateToken);
 
+    // Verifies the encrypted restriction has no padding
+    assertFalse(cabToken.encryptedRestriction.contains(String.valueOf("=")));
+
     // Checks the encrypted restriction is the correct proto format of the CredentialAccessBoundary.
     ClientSideAccessBoundary clientSideAccessBoundary =
         decryptRestriction(