PMD

By default, plugin activates if java sources available (src/main/java).

Default config contains all java checks, but some of them are disabled. Remove exclusion to enable disabled rule.

Warning

Pmd 6.0 changed rule groups. Default config was rewritten accordingly.

Output

23 PMD rule violations were found in 2 files

[Comments | CommentRequired] sample.(Sample.java:3) 
  headerCommentRequirement Required
  https://pmd.github.io/pmd-5.4.0/pmd-java/rules/java/comments.html#CommentRequired

...

Config

Tool config options with defaults:

quality {
    pmdVersion = '6.23.0'
    pmd = true // false to disable automatic plugin activation  
    pmdIncremental = false // true to enable pmd incremental analysis
}

Suppress

To suppress violation:

@SuppressWarnings("PMD.CommentRequired")

To suppress all violations:

@SuppressWarnings("PMD")

Single line could be suppressed with comment:

if (x > 5) { // NOPMD
}