src/jdk.compiler/share/classes/com/sun/tools/javac/platform/JDKPlatformProvider.java

*** 106,116 ****
              this.version = version;
          }
  
          @Override
          public Collection<Path> getPlatformPath() {
!             if (Target.lookup(version) == Target.DEFAULT) {
                  return null;
              }
  
              List<Path> paths = new ArrayList<>();
              Path file = findCtSym();
--- 106,118 ----
              this.version = version;
          }
  
          @Override
          public Collection<Path> getPlatformPath() {
!             // Comparison should be == Target.DEFAULT once --release 9
!             // is distinct from 10
!             if (Target.lookup(version).compareTo(Target.JDK1_9)  >=  0) {
                  return null;
              }
  
              List<Path> paths = new ArrayList<>();
              Path file = findCtSym();