[MINOR][DOC] Fix Java example code in Column's comments

[da-liii]

What changes were proposed in this pull request?

Fix scaladoc in Column

How was this patch tested?

None

[HyukjinKwon]

ok to test

[SparkQA]

Test build #94555 has finished for PR 22069 at commit 8520df8.

• This patch fails SparkR unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[kiszk]

Do we need to update the following similar examples, too?

Column.scala

   * {{{
   *   // Example: encoding gender string column into integer.
   *
   *   // Scala:
   *   people.select(when(people("gender") === "male", 0)
   *     .when(people("gender") === "female", 1)
   *     .otherwise(2))
   *
   *   // Java:
   *   people.select(when(col("gender").equalTo("male"), 0)
   *     .when(col("gender").equalTo("female"), 1)
   *     .otherwise(2))
   * }}}

functions.scala

   * {{{
   *   // Example: encoding gender string column into integer.
   *
   *   // Scala:
   *   people.select(when(people("gender") === "male", 0)
   *     .when(people("gender") === "female", 1)
   *     .otherwise(2))
   *
   *   // Java:
   *   people.select(when(col("gender").equalTo("male"), 0)
   *     .when(col("gender").equalTo("female"), 1)
   *     .otherwise(2))
   * }}}

[SparkQA]

Test build #4239 has finished for PR 22069 at commit 8520df8.

• This patch fails SparkR unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

Yea if there are more instances found, we better fix them together

[HyukjinKwon]

retest this please

[SparkQA]

Test build #94595 has finished for PR 22069 at commit 8520df8.

• This patch fails due to an unknown error code, -9.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

retest this please

[SparkQA]

Test build #94613 has finished for PR 22069 at commit 8520df8.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

retest this please

[SparkQA]

Test build #94620 has finished for PR 22069 at commit 8520df8.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

@sadhen what do you think of @Kisks 's comment -- a few more occurrences maybe?

[srowen]

I'm going to merge this, as the additional example quoted above should actually work, assuming one imported the 'col' function. In Java, people("foo") would be wrong but col("foo") is not (necessarily).