Merge pull request #388 from jglick/NPE-JENKINS-71078

[JENKINS-71078] Better report lack of AWS credentials

Author: jglick

src/main/java/io/jenkins/plugins/artifact_manager_jclouds/s3/S3BlobStore.java

@@ -157,6 +157,9 @@ private Supplier<Credentials> getCredentialsSupplier() throws IOException {
 
         if (getConfiguration().getDisableSessionToken()) {
             AmazonWebServicesCredentials awsCredentials = CredentialsAwsGlobalConfiguration.get().getCredentials();
+            if (awsCredentials == null) {
+                throw new IOException("No static AWS credentials found");
+            }
             accessKeyId = awsCredentials.getCredentials().getAWSAccessKeyId();
             secretKey = awsCredentials.getCredentials().getAWSSecretKey();
             sessionToken = "";