Hands-On Enterprise Java Microservices with Eclipse MicroProfile

Custom converters

If your application defines Java types that do not provide any of these three cases covered by the automatic converters, MicroProfile Config can still provide conversion using custom converters that extend the org.eclipse.microprofile.config.spi.Converter interface defined in the following:

public interface Converter<T> {
    /**
     * Configure the string value to a specified type
     * @param value the string representation of a property value.
     * @return the converted value or null
     *
     * @throws IllegalArgumentException if the value cannot be converted to        the specified type.
     */
    T convert(String value);

You have to write an implementation of org.eclipse.microprofile.config.spi.Converter, then add its name to the /META-INF/services/org.eclipse.microprofile.config.spi.Converter ...