default @NotNull T decoration(final @NotNull TextDecoration decoration, final boolean flag) {
    return this.decoration(decoration, TextDecoration.State.byBoolean(flag));
  }
Sets the state of a decoration.

@param decoration the decoration
@param flag {@code true} if this object should have the decoration, {@code false} if
    this object should not have the decoration
@return an object ({@code T})
@since 4.10.0
api/src/main/java/net/kyori/adventure/text/format/StyleSetter.java