Implement Display trait for DidDocument (print as json)

Signed-off-by: Patrik Stas <[email protected]>

did_doc/src/schema/did_doc.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::fmt::Display;
 
 use did_parser::{Did, DidUrl};
 use serde::{Deserialize, Serialize};
@@ -42,6 +43,13 @@ pub struct DidDocument<E> {
     extra: HashMap<String, Value>,
 }
 
+impl Display for DidDocument<()> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let json = serde_json::to_string(self).unwrap();
+        write!(f, "{}", json)
+    }
+}
+
 impl<E> DidDocument<E> {
     pub fn builder(id: Did) -> DidDocumentBuilder<E> {
         DidDocumentBuilder::new(id)