Fixing policy view interface not loading issue

[madawas]

Purpose

When a policy is created and viewed the policy using the policy view icon the page keeps loading sometimes due to an undefined deviceGroups variable inside the policyPayloadObj. The purpose of this PR is to fix this issue. Resolves wso2/product-iots#1681

Goals

Fixing the above issue

Approach

This commit fixes this issue by improving the code where the null check has been made to check if the deviceGroup is null. Also made few improvements in the code where the checks have been made.

User stories

N/A

Release note

N/A

Documentation

N/A, This is a bug fix.

Training

N/A

Certification

N/A

Marketing

N/A

Automation tests

• Unit tests

  Code coverage information

• Integration tests

  Details about the test cases and coverage

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? yes
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes

Samples

N/A

Related PRs

N/A

Migrations (if applicable)

N/A

Test environment

Ubuntu 16.04, JDK 1.8.0_161,H2

Learning

N/A