RunnerClassLoader sanitizeName cannot handle 0 length name argument 
I've been working to make camel-k use the Quarkus fast-jar package format. With Kotlin based Camel routes, the application statup fails.

I'm no Kotlin expert, but its bootstrap is calling `getResources("")` on the `ClassLoader` (not sure if that's valid or not). When the [name argument](https://github.com/quarkusio/quarkus/blob/993a5667fbb51aec5677e30e7210d07bb3be529a/independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java#L132) passed to `RunnerClassLoader.sanitizeName` is an empty string, then an exception is thrown:

```
2021-01-25 13:24:08,916 ERROR [io.qua.run.Application] (main) Failed to start application (with profile prod): 2021-01-25 14:29:11,572 ERROR [io.qua.run.Application] (main) Failed to start application (with profile prod): java.lang.StringIndexOutOfBoundsException: String index out of range: 0
	at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:47)
	at java.base/java.lang.String.charAt(String.java:693)
	at io.quarkus.bootstrap.runner.RunnerClassLoader.sanitizeName(RunnerClassLoader.java:150)
	at io.quarkus.bootstrap.runner.RunnerClassLoader.findResources(RunnerClassLoader.java:180)
	at java.base/java.lang.ClassLoader.getResources(ClassLoader.java:1467)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.rawClassPathFromKeyResourcePath(jvmClasspathUtil.kt:130)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.classPathFromTypicalResourceUrls(jvmClasspathUtil.kt:143)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt$classpathFromClassloader$1.invoke(jvmClasspathUtil.kt:87)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt$classpathFromClassloader$1.invoke(jvmClasspathUtil.kt)
	at kotlin.sequences.FlatteningSequence$iterator$1.ensureItemIterator(Sequences.kt:315)
	at kotlin.sequences.FlatteningSequence$iterator$1.hasNext(Sequences.kt:303)
	at kotlin.sequences.FilteringSequence$iterator$1.calcNext(Sequences.kt:169)
	at kotlin.sequences.FilteringSequence$iterator$1.hasNext(Sequences.kt:194)
	at kotlin.sequences.SequencesKt___SequencesKt.toCollection(_Sequences.kt:752)
	at kotlin.sequences.SequencesKt___SequencesKt.toMutableList(_Sequences.kt:782)
	at kotlin.sequences.SequencesKt___SequencesKt.toList(_Sequences.kt:773)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.classpathFromClassloader(jvmClasspathUtil.kt:92)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.scriptCompilationClasspathFromContextOrNull(jvmClasspathUtil.kt:275)
	at kotlin.script.experimental.jvm.util.JvmClasspathUtilKt.scriptCompilationClasspathFromContext(jvmClasspathUtil.kt:298)
	at kotlin.script.experimental.jvm.JvmScriptCompilationKt.dependenciesFromClassloader(jvmScriptCompilation.kt:57)
	at kotlin.script.experimental.jvm.JvmScriptCompilationKt.dependenciesFromClassloader$default(jvmScriptCompilation.kt:54)
```

diff --git a/independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java b/independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java
index 053f4e32e58..ecaa699dcb0 100644
--- a/independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java
+++ b/independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java
@@ -147,7 +147,7 @@ protected URL findResource(String name) {
     }
 
     private String sanitizeName(final String name) {
-        if (name.charAt(0) == '/') {
+        if (name.length() > 0 && name.charAt(0) == '/') {
             return name.substring(1);
         }
         return name;
['independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/RunnerClassLoader.java']