Add new project for GS file system and recoverable writer. This includes FileSystemFactory SPI wireup, but with no recoverable writer (yet).

Add interfaces to abstract away direct access to the Google Storage API, both to simplify that access and to make it mockable.

…orage

Add GSBlobStorage, an implementation of BlobStorage against the Google Storage API.

Add some utility functions used by the recoverable writer. Includes unit tests.

Add MockBlobStorage, an implementation of BlobStorage against an in-memory store.

Implements RecoverableWriter against the BlobStorage abstraction and wires up HadoopFileSystem.createRecoverableWriter for GS. Includes unit tests.

Rename BlobStorage and GSBlobStorage to GSBlobStorage and GSBlobStorageImpl
Rename BlobStorage.write to BlobStorage#writeBlob
Remove ability to specify blob content type
Introduce GSBlobIdentifier abstraction
Remove BlobId normalization (no longer needed)
Move nested interfaces/classes to bottom
Add count<=32 precondition for GSBlobStorageImpl#compose
Other code improvements

…base classes for new scheme/project

Remove unnecessary config options
Better handle optional config options
Change WRITER_CHUNK_SIZE to use .memoryType() instead of .intType() and add check that value is multiple of 256KB
Make HadoopFileSystem and FileSystem aware of gs: scheme and flink-gs-fs-hadoop project

…ements

Refactor utilities
Validate gs scheme in parseUri
Remove GSRecoverableWriteState, replace with immutable GSResumeRecoverable and private state in GSRecoverableFsDataOutputStream
Fix commit, commitAfterRecovery, cleanupRecoverableState, and requiresCleanupOfRecoverableState to implement proper commit and cleanup algorithms

Exclude javax.annotation-api artifact because of its GPLv2 license, which cannot be included in Flink artifacts. Everything seems to build and run fine without it.

…w feedback

Remove unnecessary throw clauses
Inline call to preconditions.checkNotNull
Use unmodifiable list for component object ids in GSResumeRecoverable
Overload GSBlobStorage#writeBlob to allow setting chunk size, remove setChunkSize on GSBlobStorage#WriteChannel

…ing separating commit vs. resume recoverables

Separate commit vs. resume recoverables
Refactor utility functions
Add javadoc comments

… progress)

…enses files

…overForCommit