Subsets model

Extend Subset model.

Crops

Add crops to Subset:

/** The crops. */
@ElementCollection(fetch = FetchType.EAGER)
@CollectionTable(name = "subset_crops", joinColumns = @JoinColumn(name = "subsetId"),
		// index
		indexes = { @Index(columnList = "subsetId, crop") })
@Column(name = "crop", nullable = false, length = 20)
@JsonView({ JsonViews.Minimal.class })
private Set<String> crops;

1. Add crop to SubsetFilter

Other properties

1. String date, a MCPD date (@Column(length = 8))
2. String source, generally a URL. (@Column(length = 200))