replaced String check isBlank() (JDK >= 11) with .trim().isEmpty() (conform to java 7, which is set in the gradle build config)
replaced String check isBlank() (JDK >= 11) with .trim().isEmpty() (conform to java 7, which is set in the gradle build config)

Signed-off-by: Philipp Seeger <09130680c10cd4f584022c93bd2dbe26fd06a697@googlemail.com>

Audiveris/audiveris,Audiveris/audiveris