https://docs.oracle.com/javase/jp/18/docs/api/java.desktop/javax/swing/plaf/BorderUIResource.EmptyBorderUIResource.html
BorderUIResource.EmptyBorderUIResource (Java SE 18 & JDK 18)
declaration: module: java.desktop, package: javax.swing.plaf, class: BorderUIResource, class: EmptyBorderUIResource
java sejdk