code: @Deprecated
      public boolean isExplicit(StandardPlural start, StandardPlural end) {
          return matrix.get(start, end) != null;
      }
docs: Returns whether the appropriate plural category for a range from start to end
  is explicitly in the data (vs given an implicit value). See also {@link #get}.
  
  @param start
  plural category for the start of the range
  @param end
  plural category for the end of the range
  @return whether the value for (start,end) is explicit or not.
  @deprecated This API is ICU internal only.
  @hide draft / provisional / internal are hidden on Android