Change MFiles.create to be Nonnull

cdm/core/src/main/java/thredds/inventory/MFileProvider.java

@@ -6,7 +6,6 @@
 package thredds.inventory;
 
 import java.io.IOException;
-import javax.annotation.Nullable;
 
 /**
  * A Service Provider of {@link thredds.inventory.MFile}.
@@ -22,12 +21,10 @@ default boolean canProvide(String location) {
   }
 
   /**
-   * Create an {@link thredds.inventory.MFile} from a given location if it exists and is readable, otherwise return
-   * null.
+   * Create an {@link thredds.inventory.MFile} from a given location, the file may or may not exist
    *
    * @param location location of a file or .
    * @return {@link thredds.inventory.MFile}
    */
-  @Nullable
   MFile create(String location) throws IOException;
 }

cdm/core/src/main/java/thredds/inventory/MFiles.java

@@ -7,7 +7,7 @@
 
 import java.io.IOException;
 import java.util.ServiceLoader;
-import javax.annotation.Nullable;
+import javax.annotation.Nonnull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import thredds.filesystem.MFileOS;
@@ -22,14 +22,13 @@ public class MFiles {
   private static final Logger logger = LoggerFactory.getLogger(NcmlReader.class);
 
   /**
-   * Create an {@link thredds.inventory.MFile} from a given location if it exists and is readable, otherwise return
-   * null.
+   * Create an {@link thredds.inventory.MFile} from a given location, the file may or may not exist
    *
    * @param location location of file (local or remote) to be used to back the MFile object
    * @return {@link thredds.inventory.MFile}
    */
-  @Nullable
-  public static MFile create(String location) {
+  @Nonnull
+  public static MFile create(@Nonnull String location) {
     MFileProvider mFileProvider = null;
 
     // look for dynamically loaded MFileProviders
@@ -40,12 +39,13 @@ public static MFile create(String location) {
       }
     }
 
-    MFile mfile = null;
     try {
-      mfile = mFileProvider != null ? mFileProvider.create(location) : MFileOS.getExistingFile(location);
+      if (mFileProvider != null) {
+        return mFileProvider.create(location);
+      }
     } catch (IOException ioe) {
       logger.error("Error creating MFile at {}.", location, ioe);
     }
-    return mfile;
+    return new MFileOS(location);
   }
 }

cdm/core/src/main/java/ucar/nc2/internal/ncml/AggDataset.java

@@ -30,6 +30,7 @@ class AggDataset implements Comparable<AggDataset> {
   private static final boolean debugOpenFile = false;
   private static final boolean debugRead = false;
 
+  @Nullable
   private final MFile mfile;
   private final Set<Enhance> enhance; // used by Fmrc to read enhanced datasets
   @Nullable
@@ -71,7 +72,7 @@ protected AggDataset(MFile mfile, @Nullable Object spiObject, @Nullable Element
   protected AggDataset(String cacheLocation, String location, @Nullable String id,
       @Nullable EnumSet<Enhance> wantEnhance, @Nullable ucar.nc2.util.cache.FileFactory reader,
       @Nullable Object spiObject, @Nullable Element ncmlElem) {
-    this.mfile = MFiles.create(location); // may be null
+    this.mfile = location == null ? null : MFiles.create(location);
     this.cacheLocation = cacheLocation;
     this.id = id;
     this.enhance = (wantEnhance == null) ? NetcdfDataset.getEnhanceNone() : wantEnhance;

cdm/core/src/main/java/ucar/nc2/iosp/AbstractIOServiceProvider.java

@@ -165,7 +165,7 @@ public boolean syncExtend() throws IOException {
   public long getLastModified() {
     if (location != null) {
       MFile file = MFiles.create(location);
-      return file != null ? file.getLastModified() : 0;
+      return file.getLastModified();
     } else {
       return 0;
     }

cdm/s3/src/main/java/thredds/inventory/s3/MFileS3.java

@@ -332,7 +332,6 @@ public String getProtocol() {
       return protocol;
     }
 
-    @Nullable
     @Override
     public MFile create(String location) throws IOException {
       try {

cdm/zarr/src/main/java/thredds/inventory/zarr/MFileZip.java

@@ -200,7 +200,6 @@ public boolean canProvide(String location) {
       return location != null && location.contains(ext);
     }
 
-    @Nullable
     @Override
     public MFile create(String location) throws IOException {
       return new MFileZip(location);