https://download.pegasus.isi.edu/pegasus/debian/dists/squeeze/main/binary-amd64/Packages

Pegasus 4.9.0 is incompatible with openjdk-7-jre. In [2], you can see a related error.

However, the package file has the following information:
Depends: openjdk-8-jre | openjdk-8-jre-headless | openjdk-7-jre | openjdk-7-jre-headless | openjdk-6-jre | openjdk-6-jre-headless, perl, python, python-openssl, libc6 (>= 2.14), libgcc1 (>= 1:3.0), libmariadbclient18 (>= 5.5.36), libstdc++6 (>= 4.1.1), zlib1g (>= 1:1.1.4)

Therefore, it allows the installation of an incompatible version of java.

I hope that you can forward this email to the maintainers.

Best,

[1] https://download.pegasus.isi.edu/pegasus/debian/dists/squeeze/main/binary-amd64/Packages

[2] Error: pegasus and java 1.8.0
2018-11-06 11:10:32,430 INFO: pegasus-plan --conf /home/mosorio/workflow/soykb/conf/distributed/pegasus.conf --dir . --relative-dir wf-20181106-111027 --sites execution --output-site isi_obelix --staging isi_obelix --dax soykb.dax
Exception in thread "main" java.lang.UnsupportedClassVersionError: edu/isi/pegasus/planner/client/CPlanner : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:808)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:442)
at java.net.URLClassLoader.access$100(URLClassLoader.java:64)
at java.net.URLClassLoader$1.run(URLClassLoader.java:354)
at java.net.URLClassLoader$1.run(URLClassLoader.java:348)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:347)
at java.lang.ClassLoader.loadClass(ClassLoader.java:430)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:323)
at java.lang.ClassLoader.loadClass(ClassLoader.java:363)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

[mosorio@soykb soykb]$ java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)