Display docs correctly in hover

What
===
Display docs are plaintext in hover, instead of inside a GitHub markdown
fenced markdown code block.

Why
===
Hover text can be made up of multiple MarkedStrings where a MarkedString
is either plaintext, or a codeblock for a code language. Docs are
usually intended to be displayed as plaintext (in markdown), with the
code blocks included alongside it. The docs shouldn't be returned as one
of the code blocks.

Reference
===
https://microsoft.github.io/language-server-protocol/specification#textDocument_hover

2 files changed, 40 insertions, 4 deletions

diff --git a/src/main/java/org/javacs/JavaLanguageServer.java b/src/main/java/org/javacs/JavaLanguageServer.java
index 2d2e3bc..9d5b33d 100644
--- a/src/main/java/org/javacs/JavaLanguageServer.java
+++ b/src/main/java/org/javacs/JavaLanguageServer.java
@@ -641,16 +641,18 @@ class JavaLanguageServer extends LanguageServer {
         var el = activeFileCache.element(line, column);
         if (!el.isPresent()) return Optional.empty();
 
-        // Add code hover message
         var result = new ArrayList<MarkedString>();
-        var code = hoverCode(el.get());
-        result.add(new MarkedString("java", code));
+
         // Add docs hover message
         var docs = hoverDocs(el.get());
         if (docs.isPresent()) {
-            result.add(new MarkedString("markdown", docs.get()));
+            result.add(new MarkedString(docs.get()));
         }
 
+        // Add code hover message
+        var code = hoverCode(el.get());
+        result.add(new MarkedString("java", code));
+
         return Optional.of(new Hover(result));
     }
 
diff --git a/src/main/java/org/javacs/lsp/MarkedString.java b/src/main/java/org/javacs/lsp/MarkedString.java
index d042d78..280225b 100644
--- a/src/main/java/org/javacs/lsp/MarkedString.java
+++ b/src/main/java/org/javacs/lsp/MarkedString.java
@@ -1,12 +1,46 @@
 package org.javacs.lsp;
 
+import java.io.IOException;
+
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.TypeAdapter;
+
+@JsonAdapter(MarkedString.Adapter.class)
 public class MarkedString {
     public String language, value;
 
     public MarkedString() {}
 
+    public MarkedString(String value) {
+        this.value = value;
+    }
+
     public MarkedString(String language, String value) {
         this.language = language;
         this.value = value;
     }
+
+    public static class Adapter extends TypeAdapter<MarkedString> {
+        @Override
+        public void write(JsonWriter out, MarkedString markedString) throws IOException {
+            if (markedString.language == null) {
+                out.value(markedString.value);
+            } else {
+                out.beginObject();
+                out.name("language");
+                out.value(markedString.language);
+                out.name("value");
+                out.value(markedString.value);
+                out.endObject();
+            }
+        }
+
+        @Override
+        public MarkedString read(JsonReader reader) throws IOException {
+          throw new UnsupportedOperationException("Deserializing MarkedString's is unsupported.");
+        }
+    }
 }