Why key type ecdsa-sha2-nistp256 is unsupported?

[fsdevblog]

I'am trying to use net-ssh and receive the error described bellow

jruby-9.1.15.0 :001 > require "net/ssh"
 => true 
jruby-9.1.15.0 :002 > Net::SSH.start('myhost.dev', 'username' password: 'password', verbose: Logger::DEBUG){|ssh| puts ssh.exec!('hostname')}
D, [2018-01-17T14:24:29.633089 #26123] DEBUG -- net.ssh.transport.session[7d0]: establishing connection to myhost.dev:22
D, [2018-01-17T14:24:29.884816 #26123] DEBUG -- net.ssh.transport.session[7d0]: connection established
I, [2018-01-17T14:24:29.888234 #26123]  INFO -- net.ssh.transport.server_version[7d2]: negotiating protocol version
D, [2018-01-17T14:24:29.888926 #26123] DEBUG -- net.ssh.transport.server_version[7d2]: local is `SSH-2.0-Ruby/Net::SSH_4.2.0 java'
D, [2018-01-17T14:24:29.952538 #26123] DEBUG -- net.ssh.transport.server_version[7d2]: remote is `SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8'
NotImplementedError: unsupported key type `ecdsa-sha2-nistp256'
        from /home/qpi/.rvm/gems/jruby-9.1.15.0@some_gem/gems/net-ssh-4.2.0/lib/net/ssh/buffer.rb:286:in `read_keyblob'

Error was raised from buffer.rb:286:in read_keyblob. Here the part of code which raising the error

unless defined?(OpenSSL::PKey::EC)
    raise NotImplementedError, "unsupported key type `#{type}'"

Ok.. lets check, defined OpenSSL::PKey::EC or not:

jruby-9.1.15.0 :003 > defined?(OpenSSL::PKey::EC) ? 'defined' : 'not defined'
 => "defined"

What am I doing wrong?

When i use ruby (not jruby), everything works fine

[fsdevblog]

Not a real solution but I found a hack that does the trick for me.
Before Net::SSH.start, put these 2 lines.

Net::SSH::Transport::Algorithms::ALGORITHMS.values.each { |algs| algs.reject! { |a| a =~ /^ecd(sa|h)-sha2/ } }
Net::SSH::KnownHosts::SUPPORTED_TYPE.reject! { |t| t =~ /^ecd(sa|h)-sha2/ }

https://stackoverflow.com/questions/48301264/why-key-type-ecdsa-sha2-nistp256-is-unsupported