ISSUE-631 : Schema Registry numeric properties cannot be set via a property file

[heritamas]

During initialization property file is read into a Properties object and
validated against a predefined set of rules. However, it was implicitly
assumed, that property values can only String typed.

This fix adds the necessary conversion beside the already existing validation.

FIxes #631

[raju-saravanan]

Thanks, @heritamas for raising this PR. Overall LGTM, left a few minor comments.

[kamalcph]

LGTM.

[raju-saravanan]

+1 LGTM, thanks @heritamas for the PR. I will merge this PR once the exception class has been updated with the license header.

[kamalcph]

@heritamas @raju-saravanan

I usually avoid taking extra fields if it can be inferred from other fields. Can we avoid using the Converter and use the Type field instead? I was thinking something like below in ConfigEntry class:

    @SuppressWarnings("unchecked")
    public static <T> T parseValue(Class<T> clazz, Object value) {
        if (clazz.equals(String.class)) {
            return (T) String.valueOf(value);
        } else if (clazz.equals(Integer.class)) {
            try {
                return (T) Integer.valueOf(value.toString());
            } catch (NumberFormatException ex) {
                throw new ConfigTypeConversionException(ex.getMessage(), ex);
            }
        } else if (clazz.equals(Long.class)) {
            return (T) Long.valueOf(value.toString());
        } else {
            throw new ConfigTypeConversionException("Found " + value.getClass() + " instead of " + clazz + " for value: " + value);
        }
    }

finalValue = ConfigEntry.parseValue(configEntry.type(), value);

I'm fine with both approaches.

[heritamas]

@kamalcph , regarding your comment:
I feel, whatever approach we choose, it would not be elegant, or clean - class casting would remain somewhere in the code.

Would it worth to refactor Property handling to a typed solution, like this?

[kamalcph]

Adding a new dependency may not worth it. Let's go with your approach.

[raju-saravanan]

@heritamas and @kamalcph I gonna go ahead and merge this PR.