Logstash-plugin missing from yum repo?

I am updating from a 1.x installation to 2.3 on a CentOS 6 server. I removed the 1.x install using yum, saving the config files. I then installed 2.3 using this procedure: https://www.elastic.co/guide/en/logstash/current/installing-logstash.html#_yum. I checked logstash.log after starting the logstash service and saw this: Couldn't find any input plugin named 'collectd'. I followed the instructions from here: https://www.elastic.co/guide/en/logstash/current/working-with-plugins.html to add the collectd plug in, but the logstash-plugin executable seems to be missing:

[root@Analytics logstash]# logstash-plugin list
-bash: logstash-plugin: command not found
[root@Analytics logstash]#

Is the logstash-plugin executable not included in the RPM? Or is it installed in some non-standard directory?

So this file doesn't exist?

# /opt/logstash/bin/logstash-plugin
    bin/logstash-plugin [OPTIONS] SUBCOMMAND [ARG] ...

    SUBCOMMAND                    subcommand
    [ARG] ...                     subcommand arguments

    install                       Install a plugin
    uninstall                     Uninstall a plugin
    update                        Update a plugin
    pack                          Package currently installed plugins
    unpack                        Unpack packaged plugins
    list                          List all installed plugins

    -h, --help                    print help

Ah. Didn't realize it was installed in /opt. I expect somewhere in /usr.

Ok, now that I can run logstash-plugin I get this:

[root@Analytics bin]# ./logstash-plugin install logstash-input-collectd
Validating logstash-input-collectd
Plugin logstash-input-collectd does not exist
ERROR: Installation aborted, verification failed for logstash-input-collectd

My 1.x logstash config has this in it:

input {
  lumberjack {
    type => "logs"
    port => 5043
    ssl_certificate => "/etc/ssl/certs/lumberjack.crt"
    ssl_key => "/etc/ssl/keys/lumberjack.key"
    tags => ["lumberjack"]
  collectd {
    tags => ["collectd"]
  file {
    type => "replication"
    path => "/var/log/replication.log"

I notice that there is a logstash-codec-collectd plug-in. I'm guessing the collectd plug-in changed from 1.x to 2.x and I need to update my config file to reflect the change?

It's a codec, not an input - https://github.com/logstash-plugins/logstash-codec-collectd