ICU-21249 API signature file for ICU 68

Also fixed some API docs missing @provisional

icu4j/main/classes/core/src/com/ibm/icu/number/FormattedNumber.java

@@ -127,6 +127,7 @@ public class FormattedNumber implements FormattedValue {
      *
      * @return `MeasureUnit`.
      * @draft ICU 68
+     * @provisional This API might change or be removed in a future release.
      */
     public MeasureUnit getOutputUnit() {
         return this.outputUnit;

icu4j/main/classes/core/src/com/ibm/icu/text/DateFormat.java

@@ -538,29 +538,34 @@ public abstract class DateFormat extends UFormat {
     /**
      * Hour Cycle
      * @draft ICU 67
+     * @provisional This API might change or be removed in a future release.
      */
     public enum HourCycle {
         /**
          * hour in am/pm (0~11)
          * @draft ICU 67
+         * @provisional This API might change or be removed in a future release.
          */
         HOUR_CYCLE_11,
 
         /**
          * hour in am/pm (1~12)
          * @draft ICU 67
+         * @provisional This API might change or be removed in a future release.
          */
         HOUR_CYCLE_12,
 
         /**
          * hour in day (0~23)
          * @draft ICU 67
+         * @provisional This API might change or be removed in a future release.
          */
         HOUR_CYCLE_23,
 
         /**
          * hour in day (1~24)
          * @draft ICU 67
+         * @provisional This API might change or be removed in a future release.
          */
         HOUR_CYCLE_24;
     };
@@ -2354,7 +2359,7 @@ public abstract class DateFormat extends UFormat {
             GregorianCalendar cal = new GregorianCalendar();
             CAL_FIELD_COUNT = cal.getFieldCount();
             CAL_FIELDS = new Field[CAL_FIELD_COUNT];
-            FIELD_NAME_MAP = new HashMap<String, Field>(CAL_FIELD_COUNT);
+            FIELD_NAME_MAP = new HashMap<>(CAL_FIELD_COUNT);
         }
 
         // Java fields -------------------

icu4j/main/classes/core/src/com/ibm/icu/text/DateTimePatternGenerator.java

@@ -1358,6 +1358,7 @@ public class DateTimePatternGenerator implements Freezable<DateTimePatternGenera
     /**
      * Return the default hour cycle.
      * @draft ICU 67
+     * @provisional This API might change or be removed in a future release.
      */
     public DateFormat.HourCycle getDefaultHourCycle() {
       switch(getDefaultHourFormatChar()) {

icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java

@@ -502,6 +502,7 @@ public final class ULocale implements Serializable, Comparable<ULocale> {
      * @param locale the ULocale to canonicalize
      * @return the ULocale created from the canonical version of the ULocale.
      * @draft ICU 67
+     * @provisional This API might change or be removed in a future release.
      */
     public static ULocale createCanonical(ULocale locale) {
         return createCanonical(locale.getName());