### Question:
StringToDoubleConverter extends TypedConverter<String, Double> { @Nullable @Override public Double doConvert( @Nonnull String source ) throws ConversionException { try { return Double.parseDouble( source ); } catch ( NumberFormatException e ) { throw new ConversionException( "Could not convert string to a double value: " + source, e ); } } StringToDoubleConverter(); @Nullable @Override Double doConvert( @Nonnull String source );  }### Answer:
@Test public void doConvert() { Assert.assertEquals( (Double) 47.11, converter.convert( "47.11" ) ); }