question: private static boolean dateByMonth ( DateTimeFormatterBuilder bld , Collection < DateTimeFieldType > fields , boolean extended , boolean strictISO ) { boolean reducedPrec = false ; if ( fields . remove ( DateTimeFieldType . year ( ) ) ) { bld . append ( Constants . ye ) ; if ( fields . remove ( DateTimeFieldType . monthOfYear ( ) ) ) { if ( fields . remove ( DateTimeFieldType . dayOfMonth ( ) ) ) { appendSeparator ( bld , extended ) ; bld . appendMonthOfYear ( 2 ) ; appendSeparator ( bld , extended ) ; bld . appendDayOfMonth ( 2 ) ; } else { bld . appendLiteral ( '-' ) ; bld . appendMonthOfYear ( 2 ) ; reducedPrec = true ; } } else { if ( fields . remove ( DateTimeFieldType . dayOfMonth ( ) ) ) { checkNotStrictISO ( fields , strictISO ) ; bld . appendLiteral ( '-' ) ; bld . appendLiteral ( '-' ) ; bld . appendDayOfMonth ( 2 ) ; } else { reducedPrec = true ; } } } else if ( fields . remove ( DateTimeFieldType . monthOfYear ( ) ) ) { bld . appendLiteral ( '-' ) ; bld . appendLiteral ( '-' ) ; bld . appendMonthOfYear ( 2 ) ; if ( fields . remove ( DateTimeFieldType . dayOfMonth ( ) ) ) { appendSeparator ( bld , extended ) ; bld . appendDayOfMonth ( 2 ) ; } else { reducedPrec = true ; } } else if ( fields . remove ( DateTimeFieldType . dayOfMonth ( ) ) ) { bld . appendLiteral ( '-' ) ; bld . appendLiteral ( '-' ) ; bld . appendLiteral ( '-' ) ; bld . appendDayOfMonth ( 2 ) ; } return reducedPrec ; }
target:  Creates a date using the calendar date format. Specification reference: 5.2.1.