[gRPC][Protobuf tool] Illegal reflective access warning from handlebar

[daneshk]

When generating gRPC stub files and client file, the following warning messages are printed in the console.

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.github.jknack.handlebars.context.FieldValueResolver$FieldMember (file:/Library/Ballerina/distributions/ballerina-slp5/bre/lib/docerina-2.0.0-Preview5.jar) to field java.util.HashMap.table
WARNING: Please consider reporting this to the maintainers of com.github.jknack.handlebars.context.FieldValueResolver$FieldMember
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

This is already reported in the issue [1]

1. WARNING: Illegal reflective access by com.github.jknack.handlebars.context.MemberValueResolver jknack/handlebars.java#667

The code is generated as expected. check the warning message.