Add null check.

[samadpaydar3]

Add null check to prevent methods throwing NullPointerException.
This was detected by unit tests auto-generated by Randoop. It is generally considered a bad practice for a method to be called by non-null arguments but throw NullPointerException. Below, is one of these tests:

    @Test
    public void test001() throws Throwable {
        if (debug)
            System.out.format("%n%s%n", "ErrorTest0.test001");
        com.laserfiche.api.client.apiserver.TokenClientImpl tokenClientImpl1 = new com.laserfiche.api.client.apiserver.TokenClientImpl("");
        com.laserfiche.api.client.model.CreateConnectionRequest createConnectionRequest3 = new com.laserfiche.api.client.model.CreateConnectionRequest();
        java.lang.String str4 = createConnectionRequest3.getPassword();
        createConnectionRequest3.setUsername("https://signin.hi!/oauth/");
        // during test generation this statement threw an exception of type java.lang.NullPointerException in error
        com.laserfiche.api.client.model.SessionKeyInfo sessionKeyInfo7 = tokenClientImpl1.createAccessToken("", createConnectionRequest3);
    }

[github-actions]

unit-test-results

46 tests  ±0   45 ✅ ±0   1s ⏱️ ±0s
 8 suites ±0    1 💤 ±0 
 8 files   ±0    0 ❌ ±0 

Results for commit dd37101. ± Comparison against base commit b77abdb.

[github-actions]

integration-test-results-cloud

14 tests  ±0   14 ✅ ±0   9s ⏱️ -1s
 2 suites ±0    0 💤 ±0 
 2 files   ±0    0 ❌ ±0 

Results for commit dd37101. ± Comparison against base commit b77abdb.

[github-actions]

integration-test-results-self-hosted

6 tests  ±0   6 ✅ ±0   12s ⏱️ -1s
1 suites ±0   0 💤 ±0 
1 files   ±0   0 ❌ ±0 

Results for commit dd37101. ± Comparison against base commit b77abdb.