Logstash plugin installation issue- unable to download data

Elastic Stack Logstash
3

I defined following in Environment variables of windows:

HTTP_PROXY= http://localhost:3128
HTTPS_PROXY= http://localhost:3128

and used --no-verify , which leads to following:

C:\logstash-6.6.0\bin>logstash-plugin install --no-verify logstash-input-jmx
Installing logstash-input-jmx
Error Bundler::HTTPError, retrying 1/10
Could not fetch specs from http://rubygems.org/
Error Bundler::HTTPError, retrying 2/10
Could not fetch specs from http://rubygems.org/
Error Bundler::HTTPError, retrying 3/10
Could not fetch specs from http://rubygems.org/
Error Bundler::HTTPError, retrying 4/10
Could not fetch specs from http://rubygems.org/
Error Bundler::HTTPError, retrying 5/10

any advise will be so appreciated