This plugin is a bare bones light weight plugin to merge you Minecraft in-game chat with Discord text channel chat.

I keep getting asked to make a tutorial on how to do this from scratch, and this is the plugin from an up and coming tutorial.
The link will be posted once complete.

There is some setup users will have to do on their end first, and here is the guide for that:

1 - Create a Discord App
First you will need to navigate to https://discord.com/developers/applications, login, then click "New Application" in the top right corner


2 - Name The App
Give your app a name, then click "Create"


3 - Create A Bot
After your App has been created click the "Bot" tab on the left hand side, then the "Add Bot" button on the right of the main window


4 - Confirm Bot Creation
Click the "Yes, do it!" button to confirm Bot creation


5 - Copy Bot Token
Now that your wild bot has appeared, we will need to use it's secret token to activate the bot when the plugin loads. Under the Token section click "Copy". This token will go into the config.yml, you can add it in now, or wait until the end of the guide.


6 - Set Bot Permissions
We must make sure that when we invite the Bot to a server it has the required permission to operate correctly. This is done by including them in a Bot invite link. We can have one generated for us by clicking the "OAuth2" tab on the left of the screen, then under the Scopes tab check "bot". This will open up aditioanl bot permission you may need to scroll down to see. Under Bot Permissions check "View Channels" and "Send Messages"
Now there will be a generated Bot invite link for us, click copy, and we will use that link in the next step.


7 - Invite Your Bot
Paste the link we just made into your browser and navigate to that page.
Select which server you wish to add the Bot to, and click "Continue"


8 - Authorize Your Bot
You will now be presented with an authorization screen. This will display a list of permissions that authorizing will give the Bot. Make sure "Read Messages" and "Send Messages" are both checked, and click "Authorize"


9 - Confirm Authorization
If everything went well you should see an authorization screen, and the Bot should now be offline in the channel you specified in step 7


10 - Server Information
We have to supply some information about your server in the config.yml. We need to supply the Guild (Server) name and an array of channel names for each Guild we want to have chat merged. In our example, our Guild name is "Minecraft Chat" and the channel name is "in-game"


11 - Setup Config.yml
Using the information from the previous steps fill out your config.yml.


12 - Reload Plugin
Now that your config has been filled out correctly, issue the "dcm reload" command


13 - Enjoy
Your chat is now merged across your Minecraft and Discord servers. Enjoy the cross over conversation


Here is the source code for anyone wishing to expand upon this: DiscordChatMerge

It is very bare bones, without external libraries other than spigot, and is not well documented.
The main code resides in "Main" and "DiscordBot", all the other classes are simply wrappers for JS objects to JAVA (which there are libraries for).