ICU-10378 Use copy-on-write semantics when modifying pre-existing EnumSet.

X-SVN-Rev: 34331

diff --git a/icu4j/main/classes/core/src/com/ibm/icu/text/DateTimePatternGenerator.java b/icu4j/main/classes/core/src/com/ibm/icu/text/DateTimePatternGenerator.java
index 0c5928e8553088970e413c9816a95da0028797dd..cfbed390cb63b24566762a378a0f6831a04b0532 100644 (file)
--- a/icu4j/main/classes/core/src/com/ibm/icu/text/DateTimePatternGenerator.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/text/DateTimePatternGenerator.java
@@ -1597,6 +1597,7 @@ public class DateTimePatternGenerator implements Freezable<DateTimePatternGenera
                 if ((distInfo.missingFieldMask & SECOND_AND_FRACTIONAL_MASK) == FRACTIONAL_MASK
                         && (missingFields & SECOND_AND_FRACTIONAL_MASK) == SECOND_AND_FRACTIONAL_MASK) {
                     resultPatternWithMatcher.pattern = resultPattern;
+                    flags = EnumSet.copyOf(flags);
                     flags.add(DTPGflags.FIX_FRACTIONAL_SECONDS);
                     resultPattern = adjustFieldTypes(resultPatternWithMatcher, source, flags, options);
                     distInfo.missingFieldMask &= ~FRACTIONAL_MASK; // remove bit