src/main/java/org/jfree/graphics2d/svg/StandardFontMapper.java
@Override
    public String mapFont(String family) {
        Args.nullNotPermitted(family, "family");
        String alternate = this.alternates.get(family);
        if (alternate != null) {
            return alternate;
        }
        return family;
    }
@Override
    public String mapFont(String family) {
        Args.nullNotPermitted(family, "family");
        String alternate = this.alternates.get(family);
        if (alternate != null) {
            return alternate;
        }
        return family;
    }
Maps the specified font family name to an alternative, or else returns
the same family name.

@param family  the font family name ({@code null} not permitted).

@return The same font family name or an alternative (never {@code null}).