Minor code and formatting adjustments

plugins/jupyter-integration/build.gradle

@@ -13,10 +13,10 @@ dependencies {
         exclude(group: "org.slf4j")
     }
 
-
     implementation group: "net.sf.opencsv", name: "opencsv", version: opencsv_version  // Apache 2.0
     implementation group: "commons-io", name: "commons-io", version: commons_io_version  // Apache 2.0
 
+
     // --- Test Compile ---
     testImplementation project(path: ":dbms", configuration: "test")
     testImplementation project(path: ":core", configuration: "tests")
@@ -89,5 +89,3 @@ java {
 licensee {
     allow('Apache-2.0')
 }
-
-

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/JupyterContentServer.java

@@ -328,5 +328,4 @@ private void error( Context ctx, int code, String message ) {
         ctx.result( String.format( "{\"message\": %s, \"reason\": null}", gson.toJson( message ) ) );
     }
 
-
 }

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/JupyterMapFS.java

@@ -34,7 +34,6 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.regex.Pattern;
-
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.calcite.avatica.util.Base64;

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/JupyterPlugin.java

@@ -17,10 +17,11 @@
 package org.polypheny.db.jupyter;
 
 import io.javalin.http.Context;
+import java.security.SecureRandom;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -43,9 +44,6 @@
 import org.polypheny.db.webui.HttpServer;
 import org.polypheny.db.webui.HttpServer.HandlerType;
 
-import java.security.SecureRandom;
-import java.util.Arrays;
-
 @Slf4j
 public class JupyterPlugin extends Plugin {
 
@@ -150,18 +148,17 @@ private boolean createContainer( DockerInstance dockerInstance ) {
 
                 if ( !this.container.waitTillStarted( this::testConnection, 20000 ) ) {
                     this.container.destroy();
-                    throw new RuntimeException( "Failed to start jupyter container" );
+                    throw new RuntimeException( "Failed to start Jupyter Server container" );
                 }
                 ConfigManager.getInstance().getConfig( CONFIG_CONTAINER_KEY ).setString( this.container.getContainerId() );
-                log.info( "Jupyter container has been deployed." );
+                log.info( "Jupyter Server container has been deployed" );
             } else {
                 this.container = maybeContainer.get();
             }
             onContainerRunning();
             return true;
         } catch ( Exception e ) {
-            e.printStackTrace();
-            log.warn( "Unable to deploy Jupyter container." );
+            log.warn( "Unable to deploy Jupyter Server container", e );
             return false;
         }
     }

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/JupyterProxy.java

@@ -17,12 +17,12 @@
 package org.polypheny.db.jupyter;
 
 import com.google.gson.Gson;
+import io.javalin.http.Context;
 import java.net.http.HttpResponse;
 import lombok.Setter;
 import lombok.extern.slf4j.Slf4j;
 import org.polypheny.db.jupyter.JupyterClient.JupyterServerException;
 import org.polypheny.db.jupyter.model.JupyterSessionManager;
-import io.javalin.http.Context;
 
 @Slf4j
 public class JupyterProxy {

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/JupyterKernel.java

@@ -211,9 +211,10 @@ public void execute( String code, String uuid ) {
      * @param variable the name of the variable the result will be stored in
      * @param expandParams whether to expand variables specified in the form ${varname}
      */
-    public void executePolyCell( String query, String uuid, String language, String namespace,
+    public void executePolyCell(
+            String query, String uuid, String language, String namespace,
             String variable, boolean expandParams ) {
-        if ( query.strip().length() == 0 ) {
+        if ( query.strip().isEmpty() ) {
             execute( "", uuid ); // properly terminates the request
             return;
         }
@@ -230,7 +231,7 @@ public void executePolyCell( String query, String uuid, String language, String
                 webSocket.sendBinary( request, true );
             }
         } catch ( Exception e ) {
-            e.printStackTrace();
+            log.error( "Exception while executing a Polypheny Notebook cell.", e );
         }
 
     }
@@ -412,7 +413,7 @@ public CompletionStage<?> onClose( WebSocket webSocket, int statusCode, String r
 
         @Override
         public void onError( WebSocket webSocket, Throwable error ) {
-            error.printStackTrace();
+            log.error( "Exception in Jupyter WebSocket.", error );
             jsm.removeKernel( kernelId );
             Listener.super.onError( webSocket, error );
         }

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/language/JupyterKernelLanguage.java

@@ -88,4 +88,3 @@ public JupyterQueryPart( String code, boolean silent, boolean allowStdin ) {
     }
 
 }
-

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/request/ContentsCreateRequest.java

@@ -21,8 +21,10 @@
 
 @Getter
 public class ContentsCreateRequest {
-    @SerializedName( "copy_from" )
+
+    @SerializedName("copy_from")
     private String copyFrom;
     private String ext;
     private String type;
+
 }

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/response/NotebookContentModel.java

@@ -20,12 +20,28 @@
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 
+/**
+ * See https://jupyter-server.readthedocs.io/en/latest/developers/rest-api.html
+ */
 @NoArgsConstructor
 public class NotebookContentModel {
-    // see https://jupyter-server.readthedocs.io/en/latest/developers/rest-api.html
 
     @Getter
-    private String name, path, created, format, mimetype, size, writable, type;
+    private String name;
+    @Getter
+    private String path;
+    @Getter
+    private String created;
+    @Getter
+    private String format;
+    @Getter
+    private String mimetype;
+    @Getter
+    private String size;
+    @Getter
+    private String writable;
+    @Getter
+    private String type;
 
     @Getter
     @SerializedName("last_modified")

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/response/NotebookModel.java

@@ -24,9 +24,11 @@
 import lombok.Setter;
 import org.polypheny.db.jupyter.model.language.JupyterKernelLanguage;
 
+/**
+ * See https://nbformat.readthedocs.io/en/latest/format_description.html
+ */
 @NoArgsConstructor
 public class NotebookModel {
-    // see https://nbformat.readthedocs.io/en/latest/format_description.html
 
     @Getter
     @Setter

plugins/jupyter-integration/src/main/java/org/polypheny/db/jupyter/model/response/PolyMetadataModel.java

@@ -29,7 +29,10 @@ public class PolyMetadataModel {
     private String cellType;
 
     @Getter
-    private String namespace, language;
+    private String namespace;
+
+    @Getter
+    private String language;
 
     @Getter
     @SerializedName("result_variable")