Suppress violations

Special annotation could be used to suppress violations: examples

Default annotation

Add dependency on the annotation artifact:

implementation "org.codehaus.mojo:animal-sniffer-annotations:1.24"

Use provided scope if you can. Annotation is configured by default, so you can simply use annotation to suppress violation:

@IgnoreJRERequirement
private Optional param;

Custom annotation

You can define your own annotation:

package com.mycompany

@Retention(RetentionPolicy.CLASS)
@Documented
@Target({ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE})
public @interface SuppressSignatureCheck {}

Configure annotation:

animalsniffer {
    annotation = 'com.mycompany.SuppressSignatureCheck'
}

Now check will skip blocks annotated with your annotation:

@SuppressSignatureCheck
private Optional param;

Ignore classes

Your project could target multiple Java versions and so reference classes, not present in a signature.

For example, your implementation could try to use Java 7 Paths and if the class is not available, fall back to the Java 6 implementation. In this case Paths could be added to the ignored classes:

animalsniffer {
    ignore 'java.nio.file.Paths'
}

Now usages of Paths will not cause warnings.

Multiple ignored classes could be defined:

animalsniffer {
    ignore 'java.nio.file.Paths', 'some.other.Class'
}

Or

animalsniffer {
    ignore 'java.nio.file.Paths'
    ignore 'some.other.Class'
}

Or by directly assigning collection:

animalsniffer {
    ignore  = ['java.nio.file.Paths', 'some.other.Class']
}

Entire packages could be ignored using asterisk:

animalsniffer {
    ignore 'some.pkg.*'
}

See more info in the documentation.