B (final java.util.Collection<? extends Number> extendsGenerics) { if (extendsGenerics == null) { throw new java.lang.NullPointerException("extendsGenerics cannot be null"); } if (this.extendsGenerics == null) this.extendsGenerics = new java.util.ArrayList<Number>(); this.extendsGenerics.addAll(extendsGenerics); return self(); }