Add javadoc to DidDocumentMetadata

Author: filip26

src/main/java/com/apicatalog/did/resolver/DidDocumentMetadata.java

@@ -1,5 +1,87 @@
 package com.apicatalog.did.resolver;
 
+import java.time.Instant;
+import java.util.Collections;
+import java.util.Set;
+
+import com.apicatalog.did.Did;
+
+/**
+ * Metadata associated with a resolved DID Document, as defined in
+ * <a href="https://www.w3.org/TR/did-core/#did-document-metadata">DID Core —
+ * DID Document Metadata</a>.
+ */
 public interface DidDocumentMetadata {
 
+    /**
+     * The timestamp when the DID Document was created.
+     *
+     * @return creation time, or {@code null} if not provided
+     */
+    default Instant created() {
+        return null;
+    }
+
+    /**
+     * The timestamp when the DID Document was last updated.
+     *
+     * @return last update time, or {@code null} if not provided
+     */
+    default Instant updated() {
+        return null;
+    }
+
+    /**
+     * Indicates whether the DID has been deactivated.
+     *
+     * @return {@code true} if deactivated, otherwise {@code false}
+     */
+    default boolean deactivated() {
+        return false;
+    }
+
+    /**
+     * A timestamp after which the DID Document should be refreshed.
+     *
+     * @return refresh time, or {@code null} if not specified
+     */
+    default Instant refresh() {
+        return null;
+    }
+
+    /**
+     * The identifier for the current version of the DID Document.
+     *
+     * @return version identifier, or {@code null} if not provided
+     */
+    default String versionId() {
+        return null;
+    }
+
+    /**
+     * The identifier of the next version of the DID Document.
+     *
+     * @return next version identifier, or {@code null} if not provided
+     */
+    default String nextVersionId() {
+        return null;
+    }
+
+    /**
+     * Equivalent identifiers for the DID, if any.
+     *
+     * @return a set of equivalent DIDs, never {@code null}
+     */
+    default Set<Did> equivalentId() {
+        return Collections.emptySet();
+    }
+
+    /**
+     * The canonical identifier for the DID.
+     *
+     * @return canonical DID, or {@code null} if not provided
+     */
+    default Did canonicalId() {
+        return null;
+    }
 }