code: protected void buildMap( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params, Builder<K, V> builder ) {
          reader.beginObject();
          while ( JsonToken.END_OBJECT != reader.peek() ) {
              String name = reader.nextName();
              K key = keyDeserializer.deserialize( name, ctx );
              V value = valueDeserializer.deserialize( reader, ctx, params );
              builder.put( key, value );
          }
          reader.endObject();
      }
docs: Build the {@link ImmutableMap} using the given builder.
  
  @param reader {@link JsonReader} used to read the JSON input
  @param ctx Context for the full deserialization process
  @param params Parameters for this deserialization
  @param builder {@link ImmutableMap.Builder} used to collect the entries