Merge changes from topics "openjdk11-java.lang.String-chars-codePoints", "openjdk11-java.lang.String-isBlank", "openjdk11-java.lang.String-lines"

* changes:
  OpenJDK 11: Merging in java.lang.String (chars() and codePoints() methods)
  OpenJDK 11: Merging in java.lang.String (lines() method)
  OpenJDK 11: Merging in java.lang.String (isBlank() method)