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

*** 951,961 ****
           * @throws IllegalStateException
           *         If the dependence on the module has already been declared
           */
          public Builder requires(Set<Requires.Modifier> mods, String mn) {
              if (name.equals(mn))
!                 throw new IllegalArgumentException("Dependence on self");
              if (requires.containsKey(mn))
                  throw new IllegalStateException("Dependence upon " + mn
                                                  + " already declared");
              requires.put(mn, new Requires(mods, mn)); // checks mn
              return this;
--- 951,961 ----
           * @throws IllegalStateException
           *         If the dependence on the module has already been declared
           */
          public Builder requires(Set<Requires.Modifier> mods, String mn) {
              if (name.equals(mn))
!                 throw new IllegalArgumentException("Dependence on self: " + mn);
              if (requires.containsKey(mn))
                  throw new IllegalStateException("Dependence upon " + mn
                                                  + " already declared");
              requires.put(mn, new Requires(mods, mn)); // checks mn
              return this;
*** 1271,1281 ****
           *
           * @see Version#parse(String)
           */
          public Builder version(String v) {
              if (version != null)
!                 throw new IllegalStateException("module version already set");
              version = Version.parse(v);
              return this;
          }
  
          /**
--- 1271,1282 ----
           *
           * @see Version#parse(String)
           */
          public Builder version(String v) {
              if (version != null)
!                 throw new IllegalStateException(
!                     "module version already set: " + version);
              version = Version.parse(v);
              return this;
          }
  
          /**
*** 1291,1301 ****
           * @throws IllegalStateException
           *         If the module main class is already set
           */
          public Builder mainClass(String mc) {
              if (mainClass != null)
!                 throw new IllegalStateException("main class already set");
              mainClass = requireJavaIdentifier("main class name", mc);
              return this;
          }
  
          /**
--- 1292,1303 ----
           * @throws IllegalStateException
           *         If the module main class is already set
           */
          public Builder mainClass(String mc) {
              if (mainClass != null)
!                 throw new IllegalStateException(
!                     "main class already set: " + mainClass);
              mainClass = requireJavaIdentifier("main class name", mc);
              return this;
          }
  
          /**
*** 1311,1321 ****
           * @throws IllegalStateException
           *         If the operating system name is already set
           */
          public Builder osName(String name) {
              if (osName != null)
!                 throw new IllegalStateException("OS name already set");
              if (name == null || name.isEmpty())
                  throw new IllegalArgumentException("OS name is null or empty");
              osName = name;
              return this;
          }
--- 1313,1324 ----
           * @throws IllegalStateException
           *         If the operating system name is already set
           */
          public Builder osName(String name) {
              if (osName != null)
!                 throw new IllegalStateException(
!                     "OS name already set: " + osName);
              if (name == null || name.isEmpty())
                  throw new IllegalArgumentException("OS name is null or empty");
              osName = name;
              return this;
          }
*** 1333,1343 ****
           * @throws IllegalStateException
           *         If the operating system architecture is already set
           */
          public Builder osArch(String arch) {
              if (osArch != null)
!                 throw new IllegalStateException("OS arch already set");
              if (arch == null || arch.isEmpty())
                  throw new IllegalArgumentException("OS arch is null or empty");
              osArch = arch;
              return this;
          }
--- 1336,1347 ----
           * @throws IllegalStateException
           *         If the operating system architecture is already set
           */
          public Builder osArch(String arch) {
              if (osArch != null)
!                 throw new IllegalStateException(
!                     "OS arch already set: " + osArch);
              if (arch == null || arch.isEmpty())
                  throw new IllegalArgumentException("OS arch is null or empty");
              osArch = arch;
              return this;
          }
*** 1355,1365 ****
           * @throws IllegalStateException
           *         If the operating system version is already set
           */
          public Builder osVersion(String version) {
              if (osVersion != null)
!                 throw new IllegalStateException("OS version already set");
              if (version == null || version.isEmpty())
                  throw new IllegalArgumentException("OS version is null or empty");
              osVersion = version;
              return this;
          }
--- 1359,1370 ----
           * @throws IllegalStateException
           *         If the operating system version is already set
           */
          public Builder osVersion(String version) {
              if (osVersion != null)
!                 throw new IllegalStateException(
!                     "OS version already set: " + osVersion);
              if (version == null || version.isEmpty())
                  throw new IllegalArgumentException("OS version is null or empty");
              osVersion = version;
              return this;
          }