FULL PRODUCT VERSION :
[bin 698]$ $JAVA9_HOME/bin/java -version
java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+126)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+126, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
[tmp 513]$ uname -a
Darwin Scotts-iMac.local 15.5.0 Darwin Kernel Version 15.5.0: Tue Apr 19 18:36:36 PDT 2016; root:xnu-3248.50.21~8/RELEASE_X86_64 x86_64



A DESCRIPTION OF THE PROBLEM :
A ClassLoader with a null parent ClassLoader appears to only have visibility into the java.base module. In Java 8 and earlier, such a ClassLoader would have visibility to all of the classes comprising the Java platform.

REGRESSION. Last worked in version 8u92

ADDITIONAL REGRESSION INFORMATION:
[bin 698]$ $JAVA9_HOME/bin/java -version
java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+126)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+126, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
There is a complete sample app showing the problem available at https://github.com/RedHatJava9Testing/URLClassLoader.git.

1. git clone https://github.com/RedHatJava9Testing/URLClassLoader.git
2. cd URLClassLoader
3. $JAVA9_HOME/bin/javac -d bin src/*.java
4. [URLClassLoader 525]$ $JAVA9_HOME/bin/java -cp bin TestURLClassLoader
myModule=unnamed module @1efbd816, layer=null, md=null
myModule.classLoader=jdk.internal.loader.ClassLoaders$AppClassLoader@4b6995df, parent=jdk.internal.loader.ClassLoaders$PlatformClassLoader@66048bfd
rootURL=file:/Users/starksm/workspace/URLClassLoader/bin/
Loaded class: class JavaSqlUser, loader=java.net.URLClassLoader@402f32ff
JavaSqlUser.init, SqlDateUser.module:unnamed module @6d8a00e3, loader: java.net.URLClassLoader@402f32ff
Exception in thread "main" java.lang.reflect.InvocationTargetException
at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(java.base@9-ea/Native Method)
at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(java.base@9-ea/NativeConstructorAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(java.base@9-ea/DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(java.base@9-ea/Constructor.java:453)
at TestURLClassLoader.main(TestURLClassLoader.java:24)
Caused by: java.lang.NoClassDefFoundError: java/sql/Date
at SqlDateUser.<init>(SqlDateUser.java:7)
at JavaSqlUser.<init>(JavaSqlUser.java:10)
... 5 more
Caused by: java.lang.ClassNotFoundException: java.sql.Date
at java.net.URLClassLoader.findClass(java.base@9-ea/URLClassLoader.java:384)
at java.lang.ClassLoader.loadClass(java.base@9-ea/ClassLoader.java:486)
at java.lang.ClassLoader.loadClass(java.base@9-ea/ClassLoader.java:419)
... 7 more


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
If you checkout the java8 branch, compile and run with a Java8 jdk you get the expected result:

1. git checkout java8
2. $JAVA8_HOME/bin/javac -d bin src/*.java
3. $JAVA8_HOME/bin/java -cp bin TestURLClassLoader
rootURL=file:/Users/starksm/workspace/URLClassLoader/bin/
Loaded class: class JavaSqlUser, loader=java.net.URLClassLoader@677327b6
Loaded instance: JavaSqlUser(SqlDateUser@7f31245a)

ACTUAL -
Exception in thread "main" java.lang.reflect.InvocationTargetException
at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(java.base@9-ea/Native Method)
at jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(java.base@9-ea/NativeConstructorAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(java.base@9-ea/DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(java.base@9-ea/Constructor.java:453)
at TestURLClassLoader.main(TestURLClassLoader.java:24)
Caused by: java.lang.NoClassDefFoundError: java/sql/Date
at SqlDateUser.<init>(SqlDateUser.java:7)
at JavaSqlUser.<init>(JavaSqlUser.java:10)
... 5 more
Caused by: java.lang.ClassNotFoundException: java.sql.Date
at java.net.URLClassLoader.findClass(java.base@9-ea/URLClassLoader.java:384)
at java.lang.ClassLoader.loadClass(java.base@9-ea/ClassLoader.java:486)
at java.lang.ClassLoader.loadClass(java.base@9-ea/ClassLoader.java:419)
... 7 more


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
Available at https://github.com/RedHatJava9Testing/URLClassLoader.git
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
To achieve the same behavior as seen under Java8, one has to pass the new ClassLoader.getPlatformClassLoader() value as the parent ClassLoader rather than null.