For EAPI 6+ java-pkg-opt-2_src_prepare() has eapply_user call via
java-utils-2_src_prepare() from java-utils-2.eclass. But
java-utils-2_src_prepare() call is conditional and in case when
package is build with USE=-java java-utils-2_src_prepare() is not
called, hence eapply_user is not called in src_prepare phase and
ebuild fails.
This problem is fixed by calling eapply_user if java USE is
disabled _and_ EAPI is 6+.
java-pkg-opt-2_src_prepare() {
use ${JAVA_PKG_OPT_USE} && java-utils-2_src_prepare
+ case "${EAPI:-0}" in
+ [0-5]) ;;
+ *) use ${JAVA_PKG_OPT_USE} || eapply_user ;;
+ esac
}