8193256: Configuration and ModuleLayer findModule cleanup

Reviewed-by: redestad, alanb

src/java.base/share/classes/java/lang/ModuleLayer.java

@@ -845,9 +845,8 @@ public final class ModuleLayer {
 
         return layers()
                 .skip(1)  // skip this layer
-                .map(l -> l.nameToModule)
-                .filter(map -> map.containsKey(name))
-                .map(map -> map.get(name))
+                .map(l -> l.nameToModule.get(name))
+                .filter(Objects::nonNull)
                 .findAny();
     }
 

src/java.base/share/classes/java/lang/module/Configuration.java

@@ -543,9 +543,8 @@ public final class Configuration {
         if (!parents.isEmpty()) {
             return configurations()
                     .skip(1)  // skip this configuration
-                    .map(cf -> cf.nameToModule)
-                    .filter(map -> map.containsKey(name))
-                    .map(map -> map.get(name))
+                    .map(cf -> cf.nameToModule.get(name))
+                    .filter(Objects::nonNull)
                     .findFirst();
         }