Where do I get the source code for com.sun.xml.internal package? It is part of the JDK 7 but its source files are not located in the $JAVA_HOME/src.zip . Generally the JDK souce files are located there but for this case are not.
UPDATE: To answer my own question you can download all OpenJDK source by using executing this and then linking to that source folder in Eclipse:
cat > subprojects.md5 << EOF &&
c99a63dfaf2b2f8cc549e65b790a2e7a corba.tar.bz2
d15561707ce64419f36c18e4fba6cbbe hotspot.tar.bz2
5b32371928b7aa67646b560e5c89dcde jaxp.tar.bz2
05f7c3c91f3a6a38316bb4f406798b61 jaxws.tar.bz2
07223640c22b3ea75f3df81876622ba5 langtools.tar.bz2
6d737d1623b83a7acca8c18d0e08dd3d jdk.tar.bz2
d5e109b7e2b2daab5874d650293321c8 nashorn.tar.bz2
EOF
for subproject in corba hotspot jaxp jaxws langtools jdk nashorn; do
wget -c http://hg.openjdk.java.net/jdk8u/jdk8u/${subproject}/archive/jdk8u66-b17.tar.bz2 \
-O ${subproject}.tar.bz2
done &&
md5sum -c subprojects.md5 &&
for subproject in corba hotspot jaxp jaxws langtools jdk nashorn; do
mkdir -pv ${subproject} &&
tar -xf ${subproject}.tar.bz2 --strip-components=1 -C ${subproject}
done