fix: use @nonnull for required location field in Metaschema.java

Since location is required in the Metaschema module (required: yes),
use @nonnull instead of @nullable for getLocation() and setLocation().

Author: david-waltermire

metaschema-testing/src/main/java/gov/nist/csrc/ns/metaschema/test_suite/_1_0/Metaschema.java

@@ -14,6 +14,7 @@
 import java.lang.String;
 import java.net.URI;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
 import edu.umd.cs.findbugs.annotations.Nullable;
 
 import org.apache.commons.lang3.builder.ReflectionToStringBuilder;
@@ -66,9 +67,9 @@ public IMetaschemaData getMetaschemaData() {
   /**
    * Get the URI reference to the metaschema module location.
    *
-   * @return the location URI, or {@code null} if not set
+   * @return the location URI
    */
-  @Nullable
+  @NonNull
   public URI getLocation() {
     return _location;
   }
@@ -79,7 +80,7 @@ public URI getLocation() {
    * @param value
    *          the location URI to set
    */
-  public void setLocation(@Nullable URI value) {
+  public void setLocation(@NonNull URI value) {
     _location = value;
   }