val builder = new MetadataBuilder
sql/catalyst/src/main/scala/org/apache/spark/sql/types/Metadata.scala
          val mb = new MetadataBuilder()
        val optionalMeta = new MetadataBuilder()
sql/catalyst/src/main/scala/org/apache/spark/sql/types/StructType.scala
  val baseMetadata = new MetadataBuilder()
  val summary = new MetadataBuilder()
  val age = new MetadataBuilder()
  val gender = new MetadataBuilder()
  val metadata = new MetadataBuilder()
sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/MetadataSuite.scala
  val metadata = new MetadataBuilder()
sql/catalyst/src/test/scala/org/apache/spark/sql/types/DataTypeSuite.scala
      new MetadataBuilder().putString("comment", "name of the column").build())(),
      new MetadataBuilder().putString("comment", "data type of the column").build())(),
      new MetadataBuilder().putString("comment", "comment of the column").build())()
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ddl.scala
          new MetadataBuilder().putString(COMMENT.str.toLowerCase, comment).build()
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DDLParser.scala
            val metadata = new MetadataBuilder().putString("name", columnName)
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRDD.scala
    val metadata = new MetadataBuilder
    val metadata = new MetadataBuilder()
sql/core/src/test/scala/org/apache/spark/sql/ColumnExpressionSuite.scala
        new MetadataBuilder().putString("comment", s"test comment $table").build()),
sql/core/src/test/scala/org/apache/spark/sql/sources/DDLTestSuite.scala
    val metadata = new MetadataBuilder()
sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala