Upgrade siddhi version to 4.1.0 and fix SourceMapper issue

[NisalaNiroshana]

Purpose

This will upgrade the siddhi version to 4.1.0 and introduce missing method in generated SourceMapper class

Goals

This is to release the siddhi arche-type repo with respect to SP 4.0.0 release.

Approach

Upgrade the siddhi versions and Adding the missing allowNullInTransportProperties in SourceMapper class.

User stories

NA

Release note

NA

Documentation

NA

Training

NA

Certification

NA

Marketing

NA

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

NA

Related PRs

NA

Migrations (if applicable)

NA

Test environment

java version "1.8.0_151"
Java(TM) SE Runtime Environment (build 1.8.0_151-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode)

Learning

NA