Build: Declare avro as an api dependency of iceberg-core

[devinrsmith]

iceberg-core should declare an api dependency on avro. For example, the public class org.apache.iceberg.PartitionData extends avro-specific types. In addition, there are public methods that deal with avro types, see org.apache.iceberg.avro.AvroSchemaUtil

[findepi]

For example, the public class org.apache.iceberg.PartitionData extends avro-specific types. In addition, there are public methods that deal with avro types

Can such things be statically checked so that we don't have to manually analyse API surface?

[devinrsmith]

I've often wondered the same thing (deephaven/deephaven-core#4411, deephaven/deephaven-core#4401)... it seems like it would be a very useful tool.

It's possible that something along the lines of https://github.com/revapi/revapi, https://github.com/siom79/japicmp, https://github.com/classgraph/classgraph could be used to automate the process of checking which dependencies are really api dependencies and which are implementation, but I haven't dug in further.

I see that iceberg already makes use out of revapi; I wonder if somebody familiar with that tool could chime in?

[nastra]

Adding some additional context around api vs implementation for other reviewers:

Dependencies appearing in the api configurations will be transitively exposed to consumers of the library, and as such will appear on the compile classpath of consumers. Dependencies found in the implementation configuration will, on the other hand, not be exposed to consumers, and therefore not leak into the consumers' compile classpath