[BUG] Fix problems in azure-spring-boot-service reported by sonar

[chenrujun]

Context

We use sonar to check the code quality for all Spring Cloud Azure codes.

• The sonar setting was put here: https://github.com/Azure/spring-cloud-azure-tools#sonar-analysis
• The sonar analyze result was here: https://sonarcloud.io/dashboard?id=stliu_azure-sdk-for-java

Goal

We should fix the issues in the report and finally make this report success.
Here is the summary report:
https://sonarcloud.io/summary/new_code?id=stliu_azure-sdk-for-java

Our goal is to achieve the following goals:

Sonar quality check	Goal	Current
Reliability	0 bugs	4 bugs
Security	0 vulnerabilities	0 vulnerabilities
Coverage	80%	67.4%
Maintainability	A	A
Security Review	0 security hotspots	1 security hotspots
Duplication	3%	5.6%

Solution

Sonar scan from the above report give us some hints of the code smells and bug issues. Upon the report, we list the issues that must-fix, can be ignored, and need discussion in the following.

The following issues are must-fix:

1. magic number

2. Use "==" to perform this enum comparison instead of using "equals"

3. Access scope modifier, for example: protected ctor for abstract class

4. Use the primitive boolean expression here.

5. Add a private constructor to hide the implicit public one for Utility Class
   for example: AzureStorageUtils.java

6. Either log this exception and handle it, or rethrow it with some contextual information.

7. Complete the task associated to this TODO comment.
   For example: StorageFileResource.java(L220)

8. Code cleaning.

The following issues need discussion:

Sonar report critical issues for the following code smells:

1. code complexity reduce.
2. deprecation usage of API.
3. This class has 6 parents.
4. Usage of generic wildcard type in return type.
5. Fields in a "Serializable" class should either be transient or serializable. (Security issue)

The following issues are ignored:

1. Define and throw a dedicated exception instead of using a generic one.

2. magic number 1000 used as 1000 milliseconds, or parameter in Duration.ofMinutes(5);

3. Add a constructor to the class, or provide default values.