Upgrading from 2.0.x to 3.0.x

Primary API changes

GraphIndexBuilder M parameter now represents the maximum degree of the graph, instead of half the maximum degree. (The former behavior was motivated by making it easy to make apples-to-apples comparisons with Lucene HNSW graphs.) So, if you were building a graph of M=16 with JVector2, you should build it with M=32 with JVector3.
NodeSimilarity.ReRanker renamed to Reranker
NodeSimilarity.Reranker api has changed. The interface is no longer parameterized, and the similarityTo method no longer takes a Map parameter (provided by search with the full vectors associated with the nodes returned). This is because we discovered that (in contrast with the original DiskANN design) it is more performant to read vectors lazily from disk at reranking time, since this will only have to fetch vectors for the topK nodes instead of all nodes visited.

OnHeapGraphIndex::ramBytesUsedOneNode no longer takes an int nodeLevel parameter

In-graph deletes are supported through GraphIndexBuilder.markNodeDeleted. Deleted nodes are removed when GraphIndexBuilder.cleanup is called (which is not threadsafe wrt other concurrent changes). To write a graph with deleted nodes to disk, a Map must be supplied indicating what ordinals to change the remaining node ids to -- on-disk graphs may not contain "holes" in the ordinal sequence.
GraphSearcher.search now has an experimental overload that takes a float threshold parameter that may be used instead of topK; (approximately) all the nodes with simlarities greater than the given threshold will be returned.
Binary Quantization is available as an alternative to Product Quantization. Our tests show that it's primarily suitable for ada002 embedding vectors and loses too much accuracy with smaller embeddings.

GraphIndexBuilder.complete is now cleanup.
The Bits parameter to GraphSearcher.search is no longer nullable; pass Bits.ALL instead of null to indicate that all ordinals are acceptable.

NeighborQueue, NeighborArray, and NeighborSimilarity have been renamed to NodeQueue, NodeArray, and NodeSimilarity, respectively.