36f71d6e_Tools_Javadoc_Taglets_3_4_API___Notes
[Descriptor Element] configuration [Annotation] @parameter expression="${someExpression}" default-value="value" [Required?] No [Notes] 
Specifies the expression used to calculate the value to be injected into this parameter of the Mojo at buildtime. This is commonly used to refer to specific elements in the POM, such as ${project.build.resources}, which refers to the List of resources meant to accompany the classes in the resulting jar file. The default value is used when the expression evaluates to null . NOTE: If not specified, an expression of ${} is assumed, which can only be satisfied from POM configuration or System properties. The use of '${' and '}' is required to delimit actual expressions which may be evaluated.
org.apache.maven.tools.plugin.javadoc (Maven Plugin Tools Javadoc Taglets 3.4 API)