I tried the following javadoc command:

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javadoc -source 8 -sourcepath /Users/ljanders/Documents/hg-workspaces/openjdk8/jdk8u-dev/jdk/src/share/classes -d 42test/ -doctitle "JDBC Specification JSR 221 Maintenance Release 4.2" -windowtitle "JSR 221 Maintenance Release 4.2" -header "JSR 221 Maintenance Release 4.2" -tag 'apiNote:a:API Note:' -tag 'implSpec:a:Implementation Requirements:' java.sql javax.sql
Loading source files for package java.sql...
Loading source files for package javax.sql...
Constructing Javadoc information...
/Users/ljanders/Documents/hg-workspaces/openjdk8/jdk8u-dev/jdk/src/share/classes/sun/misc/URLClassPath.java:53: error: cannot find symbol
import sun.misc.FileURLMapper;
               ^
  symbol: class FileURLMapper
  location: package sun.misc
1 error

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I also tried to use -source 8 and put JDK 8 rt.jar on the -bootclasspath:

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javadoc -source 8 -sourcepath /Users/ljanders/Documents/hg-workspaces/openjdk8/jdk8u-dev/jdk/src/share/classes -bootclasspath /Users/ljanders/Documents/hg-workspaces/openjdk8/jdk8u-dev/build/macosx-x86_64-normal-server-release/images/lib//rt.jar -d 42test/ -doctitle "JDBC Specification JSR 221 Maintenance Release 4.2" -windowtitle "JSR 221 Maintenance Release 4.2" -header "JSR 221 Maintenance Release 4.2" -tag 'apiNote:a:API Note:' -tag 'implSpec:a:Implementation Requirements:' java.sql javax.sql
javadoc: option --boot-class-path not allowed with target 1.9
1 error

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