code: private void buildMetadataColumnMap(JsonArray array) {
      if (array != null) {
        for (JsonElement columnElement : array) {
          Schema schemaObj = gson.fromJson(columnElement, Schema.class);
          String columnName = schemaObj.getColumnName();
          this.metadataColumnMap.put(columnName.toLowerCase(), schemaObj);
          this.metadataColumnList.add(columnName.toLowerCase());
        }
      }
    }
docs: Build metadata column map with column name and column schema object.
  Build metadata column list with list columns in metadata
  
  @param array Schema of all columns