Java issue from OpenJDK 15
Compiling the Java interface with OpenJDK 15 fails with the following Javadoc error (and 100 similar errors):
java_src_sdurw_math/org/robwork/sdurw_math/Rotation3Df.java:21: error: bad HTML entity {}^A\hat{X}_B & {}^A\hat{Y}_B & {}^A\hat{Z}_B
OpenJDK 15 is available in Ubuntu 20.10 and newer. In Ubuntu 20.10 the default-jdk is still OpenJDK 11.