After I perform a standard installation that includes also the pattern:
  Java Development
I found this error in /var/log/zypp/history:

# 2017-08-31 11:41:19 java-1_5_0-gcj-compat-1.5.0.0-137.24.x86_64.rpm installed
ok
# Additional rpm output:
# update-alternatives: using /usr/lib64/jvm/jre-1.5.0-gcj/bin/java to provide
/usr/bin/java (java) in auto mode
# update-alternatives: using /usr/lib64/jvm/jre-1.5.0-gcj to provide
/usr/lib64/jvm/jre-gcj (jre_gcj) in auto mode
# update-alternatives: using /usr/lib64/jvm/jre-1.5.0-gcj to provide
/usr/lib64/jvm/jre-1.5.0 (jre_1.5.0) in auto mode
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 41: sed: command not found
# /var/tmp/rpm-tmp.X23HDn: line 42: sed: command not found
# 
2017-08-31
11:41:19|install|java-1_5_0-gcj-compat|1.5.0.0-137.24|x86_64||openSUSE-Leap-42.3-0|17950505d2dd0d9958bd2d48b428932da47839f9|

The problem is that java-1_5_0-gcj-compat is installed before sed and at that
time the binaries sed used in the postinstall scriptlet, is not available yet.

A possible fix is to add this line in java-1_5_0-gcj-compat.spec:

 Requires(pre):   gcc-gij
 Requires(post):  update-alternatives
+Requires(post):  sed
 PreReq:         coreutils