Tidy up Java

[adriangonz]

Fixes #937.

Changes

• Run tidy on pom.xml.
• Add checkstyle linter to mvn validate which will flag violations of Google's Java style guide.
• Add -Xlint:all flag to mvn compile, which will flag usage of features marked as deprecated.
• Remove some dependencies which were flagged as unused by mvn dependency:analyze.
• Add pre-commit config to manage local Git hooks. There is currently a single hook configured which will run google-java-format on modified *.java files on each commit.
• Run google-java-format across all *.java files to make style consistent.
• Add note to CONTRIBUTING.md about pre-commit and Google's Java style guide.

Notes

pre-commit is a cross-language tool to handle Git hooks. We can also use it to handle python or go formatters. For python, black already offers integration out of the box and therefore could also be interesting for #947.

[adriangonz]

/cc @axsaucedo @cliveseldon

[adriangonz]

/cc @ryandawsonuk

[adriangonz]

/uncc @jklaise

[axsaucedo]

Awesome! Nice one @adriangonz !

[axsaucedo]

Are we going for 2 spaces?

[adriangonz]

@axsaucedo I'm just going with whatever google-java-format wants to do. I don't have much mileage with Java, that's what I went for a very opinionated formatter.

Google seems to like 2 spaces.

[axsaucedo]

Fair enough! I think on this one @gsunner and @cliveseldon wouuld be the main Java ones, so if they are happy then let's press the button!

[ukclivecox]

/approve

[seldondev]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cliveseldon

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [cliveseldon]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[seldondev]

failed to trigger Pull Request pipeline

• failed to create agent
• failed to calculate in repo config
• failed to load trigger config for repository SeldonIO/seldon-core for ref be8fa22
• failed to find any lighthouse configuration files in repo SeldonIO/seldon-core at sha be8fa22
• failed to process repo SeldonIO/seldon-core refref be8fa22
• failed to list files in directory /var/tmp/gitrepo660600678/.lighthouse
• open /var/tmp/gitrepo660600678/.lighthouse
• no such file or directory