FULL PRODUCT VERSION :
openjdk version "9.0.4"
OpenJDK Runtime Environment (build 9.0.4+11)
OpenJDK 64-Bit Server VM (build 9.0.4+11, mixed mode)

-and-

java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
OSX 10.12.6

A DESCRIPTION OF THE PROBLEM :
DateTimeFormatter is now adding COMMA between date and time parts.

Inconsistent with java8 and javadoc

(https://docs.oracle.com/javase/9/docs/api/java/time/format/DateTimeFormatter.html#ofLocalizedDateTime-java.time.format.FormatStyle-java.time.format.FormatStyle-)

REGRESSION. Last worked in version 8u161

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
    void 'dtf test'() {
        given:
        def testDate = LocalDateTime.parse("2009-06-03T07:03:47")
        def expected = "6/3/09 7:03 AM"
        def dtf = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT, FormatStyle.SHORT).withLocale(Locale.US)

        when:
        def actual = dtf.format(testDate)
        // actual == "6/3/09, 7:03 AM" note comma between date/time
        
        then:
        actual == expected
    }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
test passes with java8
ACTUAL -
Condition not satisfied:

actual == expected
| | |
| | 6/3/09 7:03 AM
| false
| 1 difference (93% similarity)
| 6/3/09(,) 7:03 AM
| 6/3/09(-) 7:03 AM
6/3/09, 7:03 AM

Expected :6/3/09 7:03 AM

Actual :6/3/09, 7:03 AM

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
    void 'dtf test'() {
        given:
        def testDate = LocalDateTime.parse("2009-06-03T07:03:47")
        def expected = "6/3/09 7:03 AM"
        def dtf = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT, FormatStyle.SHORT).withLocale(Locale.US)

        when:
        def actual = dtf.format(testDate)
        // actual == "6/3/09, 7:03 AM" note comma between date/time
        
        then:
        actual == expected
    }
---------- END SOURCE ----------