Extra blank line in ColumnSchema.toString after 2 level nested column group

@Test
fun `schema should not have trailing blank line after nested column group`() {
    val df = dataFrameOf(
        "a" to columnOf(1),
        "group" to columnOf(
            "b" to columnOf(2),
            "nested" to columnOf(
                "c" to columnOf(3),
                "d" to columnOf(4),
            ),
        ),
        "e" to columnOf("str"),
    )

    assertEquals(
        """
        a: Int
        group:
            b: Int
            nested:
                c: Int
                d: Int
        e: String
    """.trimIndent(),
        df.schema().toString(),
    )
}

Result:

a: Int
group:
    b: Int
    nested:
        c: Int
        d: Int

e: String

Expected result:

a: Int
group:
    b: Int
    nested:
        c: Int
        d: Int
e: String