* Add flattenSpec support to the Avro parser.
Also:
- Refactor the JSONPathParser a bit so it can share flattening code
with Avro (see ObjectFlatteners).
- Remove the JSONParser. It was only used in two places: by
UriNamespaceExtractor, and as a base for JSONToLowerParser. Migrated
the former to JSONPathParser and made the latter a standalone.
- Move GenericRecordAsMap to the Parquet extension, since the Avro
extension no longer uses it.
* Fix indentation.
* Fix equals/hashCode.
* Make using implicit system charset an error
* Use StringUtils.toUtf8() and fromUtf8() instead of String.getBytes() and new String()
* Use English locale in StringUtils.safeFormat()
* Restore comment
These objects get constructed semi-frequently (any time a parser is
deserialized) and so info logs are spammy. They'll still appear in
task logs at least once, since they're part of the task definition and
will get logged due to that.
* 1. Collections.singletonList instand of Arrays.asList; 2. close FSDataInputStream/ByteBufferInputStream for releasing resource; 3. convert com.google.common.base.Function into java.util.function.Function; 4. others code refactor
* Put each param on its own line for code style
* Revert GenericRecordAsMap back about `Function`