Remove reliance on java.util.Date in favor of the newer Date-Time APIs

[grimsa]

The classes in the current Segment Java SDK accept the old java.util.Date in method signatures, for example:

var message = TrackMessage.builder(event.documentName())
        .timestamp(java.util.Date.from(event.time()))      // <-- here we have to convert Instant to Date
        .userId(event.user().id())
        .properties(properties);

Java 8 introduced the new The Date-Time APIs (e.g. java.time.Instant), which are preferred over the old java.util.Date/Calendar for their immutability, thread safety, and expressiveness.

It seems it should be possible to add overloaded method versions to support the new Date-Time APIs without changing or removing the existing methods.

[edsonjab]

Hi @grimsa thank you for your report, we start looking into this.

[MichaelGHSeg]

Thank you for the suggestion. We're shifting development over to the new Analytics-Kotlin library, so we won't be changing the java interface at this time. We'll try to keep updated types in mind over there (but at a glance it looks like the timestamp is currently a string :) ).