Add @Nullable annotations

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/BShellConfiguration.java

@@ -21,6 +21,7 @@
 import io.ballerina.shell.Evaluator;
 import io.ballerina.shell.EvaluatorBuilder;
 import io.ballerina.shell.parser.TrialTreeParser;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -109,6 +110,7 @@ public static class Builder {
         private InputStream inputStream;
         private OutputStream outputStream;
         private long treeParsingTimeoutMs;
+        @Nullable
         private String startFile;
         private boolean isDebug;
         private boolean isDumb;

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/handlers/help/BbeTopicsProvider.java

@@ -20,6 +20,7 @@
 
 import com.google.gson.Gson;
 import io.ballerina.shell.DiagnosticReporter;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
 import java.io.IOException;
@@ -85,6 +86,7 @@ public List<String> getTopicList() {
         return topicList;
     }
 
+    @Nullable
     private String readFileAsString(String file) {
         String content = null;
         try {

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/jline/validator/ExpressionValidator.java

@@ -21,6 +21,7 @@
 import io.ballerina.compiler.syntax.tree.Node;
 import io.ballerina.compiler.syntax.tree.NodeParser;
 import io.ballerina.shell.cli.utils.IncompleteInputFinder;
+import org.jetbrains.annotations.Nullable;
 
 /**
  *  Validates user input completes as an expression.
@@ -29,6 +30,7 @@
  */
 public class ExpressionValidator implements Validator {
 
+    @Nullable
     private Validator nextInValidator;
 
     public ExpressionValidator() {
@@ -45,6 +47,6 @@ public boolean evaluate(String source) {
         IncompleteInputFinder incompleteInputFinder = new IncompleteInputFinder();
         Node parsedNode = NodeParser.parseExpression(source);
         return !parsedNode.hasDiagnostics() || !parsedNode.apply(incompleteInputFinder)
-                || nextInValidator.evaluate(source);
+                || (nextInValidator != null && nextInValidator.evaluate(source));
     }
 }

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/jline/validator/ModuleMemberValidator.java

@@ -26,6 +26,7 @@
 import io.ballerina.shell.cli.utils.IncompleteInputFinder;
 import io.ballerina.tools.text.TextDocument;
 import io.ballerina.tools.text.TextDocuments;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Validates user input as a complete module member.
@@ -34,6 +35,7 @@
  */
 public class ModuleMemberValidator implements Validator {
 
+    @Nullable
     private Validator nextInValidator;
 
     public ModuleMemberValidator() {
@@ -59,11 +61,11 @@ public boolean evaluate(String source) {
             // Sample testcase : if (x == y) { x = x + 1; x = x + 1;
             if (lastNode.kind() == SyntaxKind.FUNCTION_DEFINITION) {
                 return !lastNode.hasDiagnostics() || !lastNode.apply(incompleteInputFinder)
-                        || nextInValidator.evaluate(lastNode.toSourceCode());
+                        || (nextInValidator != null && nextInValidator.evaluate(lastNode.toSourceCode()));
             }
         }
 
         return !node.imports().isEmpty() || !parsedNode.hasDiagnostics() || !parsedNode.apply(incompleteInputFinder)
-                || nextInValidator.evaluate(source);
+                || (nextInValidator != null && nextInValidator.evaluate(source));
     }
 }

ballerina-shell/modules/shell-cli/src/main/java/io/ballerina/shell/cli/jline/validator/StatementValidator.java

@@ -21,6 +21,7 @@
 import io.ballerina.compiler.syntax.tree.Node;
 import io.ballerina.compiler.syntax.tree.NodeParser;
 import io.ballerina.shell.cli.utils.IncompleteInputFinder;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Validates user input as a complete statement.
@@ -29,6 +30,7 @@
  */
 public class StatementValidator implements Validator {
 
+    @Nullable
     private Validator nextInValidator;
 
     public StatementValidator() {
@@ -45,6 +47,6 @@ public boolean evaluate(String source) {
         IncompleteInputFinder incompleteInputFinder = new IncompleteInputFinder();
         Node parsedNode = NodeParser.parseBlockStatement("{" + source + "}");
         return !parsedNode.hasDiagnostics() || !parsedNode.apply(incompleteInputFinder)
-                || nextInValidator.evaluate(source);
+                || (nextInValidator != null && nextInValidator.evaluate(source));
     }
 }

ballerina-shell/modules/shell-cli/src/main/java/module-info.java

@@ -5,6 +5,7 @@
     requires org.jline;
     requires com.google.gson;
     requires io.ballerina.tools.api;
+    requires static org.jetbrains.annotations;
 
     exports io.ballerina.shell.cli;
     exports io.ballerina.shell.cli.handlers.help;

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/EvaluatorImpl.java

@@ -32,6 +32,7 @@
 import io.ballerina.shell.snippet.Snippet;
 import io.ballerina.shell.snippet.factory.SnippetFactory;
 import io.ballerina.shell.utils.StringUtils;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
 import java.nio.charset.Charset;
@@ -62,6 +63,7 @@ public void initialize() throws BallerinaShellException {
         }
     }
 
+    @Nullable
     @Override
     public String evaluate(String source) throws BallerinaShellException {
         try {

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/NotebookReturnValue.java

@@ -18,6 +18,8 @@
 
 package io.ballerina.shell;
 
+import org.jetbrains.annotations.Nullable;
+
 /**
  * Return value after invoking snippet.
  * Contains result as an object & exception status related to compilation
@@ -29,7 +31,7 @@ public class NotebookReturnValue {
     private final Object result;
     private final Enum<ExceptionStatus> exceptionStatus;
 
-    NotebookReturnValue(Object result, Enum<ExceptionStatus> exceptionStatus) {
+    NotebookReturnValue(@Nullable Object result, Enum<ExceptionStatus> exceptionStatus) {
         this.result = result;
         this.exceptionStatus = exceptionStatus;
     }
@@ -39,6 +41,7 @@ public class NotebookReturnValue {
         this.exceptionStatus = exceptionStatus;
     }
 
+    @Nullable
     public Object getResult() {
         return result;
     }

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/ShellReturnValue.java

@@ -18,6 +18,8 @@
 
 package io.ballerina.shell;
 
+import org.jetbrains.annotations.Nullable;
+
 /**
  * Shell Compilation class.
  * Contains package compilation & exception status related to compilation
@@ -29,7 +31,7 @@ public class ShellReturnValue {
     private final String result;
     private final Enum<ExceptionStatus> exceptionStatus;
 
-    ShellReturnValue(String result, Enum<ExceptionStatus> exceptionStatus) {
+    ShellReturnValue(@Nullable String result, Enum<ExceptionStatus> exceptionStatus) {
         this.result = result;
         this.exceptionStatus = exceptionStatus;
     }
@@ -39,6 +41,7 @@ public class ShellReturnValue {
         this.exceptionStatus = exceptionStatus;
     }
 
+    @Nullable
     public String getResult() {
         return result;
     }

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/invoker/classload/ClassLoadInvoker.java

@@ -46,6 +46,7 @@
 import io.ballerina.shell.utils.Identifier;
 import io.ballerina.shell.utils.QuotedImport;
 import io.ballerina.shell.utils.StringUtils;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.PrintStream;
 import java.util.ArrayList;
@@ -203,6 +204,7 @@ public void reset() {
         this.availableModuleDeclarations.clear();
     }
 
+    @Nullable
     @Override
     public PackageCompilation getCompilation(Collection<Snippet> newSnippets) throws InvokerException {
         if (!this.initialized.get()) {

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/invoker/classload/ImportsManager.java

@@ -27,6 +27,7 @@
 import io.ballerina.shell.utils.QuotedImport;
 import io.ballerina.tools.text.TextDocument;
 import io.ballerina.tools.text.TextDocuments;
+import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Modifier;
 import java.util.Arrays;
@@ -133,6 +134,7 @@ public void reset() {
      * @param prefix Prefix to search.
      * @return The import statement of the prefix.
      */
+    @Nullable
     public String getImport(Identifier prefix) {
         QuotedImport quotedImport = this.imports.get(prefix);
         if (quotedImport == null) {

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/invoker/classload/context/ClassLoadContext.java

@@ -20,6 +20,7 @@
 
 import io.ballerina.shell.invoker.classload.ClassLoadInvoker;
 import io.ballerina.shell.rt.InvokerMemory;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Collection;
 import java.util.List;
@@ -60,9 +61,9 @@ public ClassLoadContext(String contextId,
                             Collection<String> imports,
                             Collection<String> moduleDclns,
                             Collection<VariableContext> varDclns,
-                            Collection<String> newVarNames,
+                            @Nullable Collection<String> newVarNames,
                             String lastVarDcln,
-                            Collection<StatementContext> lastStmts) {
+                            @Nullable Collection<StatementContext> lastStmts) {
         this.lastStmts = Objects.requireNonNullElse(lastStmts, List.of());
         this.lastVarDcln = Objects.requireNonNullElse(lastVarDcln, "");
         this.contextId = Objects.requireNonNull(contextId);
@@ -88,8 +89,8 @@ public ClassLoadContext(String contextId,
                             Collection<String> imports,
                             Collection<String> moduleDclns,
                             Collection<VariableContext> varDclns,
-                            Collection<String> newVarNames,
-                            String lastVarDcln) {
+                            @Nullable Collection<String> newVarNames,
+                            @Nullable String lastVarDcln) {
         this(contextId, imports, moduleDclns, varDclns, newVarNames, lastVarDcln, null);
     }
 

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/snippet/SnippetSubKind.java

@@ -18,6 +18,8 @@
 
 package io.ballerina.shell.snippet;
 
+import org.jetbrains.annotations.Nullable;
+
 /**
  * Snippet sub type to further categorize snippets.
  *
@@ -102,6 +104,7 @@ public boolean hasError() {
         return error != null;
     }
 
+    @Nullable
     public String getError() {
         return error;
     }

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/snippet/factory/BasicSnippetFactory.java

@@ -72,6 +72,7 @@
 import io.ballerina.shell.snippet.types.ModuleMemberDeclarationSnippet;
 import io.ballerina.shell.snippet.types.StatementSnippet;
 import io.ballerina.shell.snippet.types.VariableDeclarationSnippet;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -124,6 +125,7 @@ public class BasicSnippetFactory extends SnippetFactory {
             Map.entry(DoStatementNode.class, SnippetSubKind.DO_STATEMENT)
     );
 
+    @Nullable
     @Override
     public ImportDeclarationSnippet createImportSnippet(Node node) {
         if (node instanceof ImportDeclarationNode importDeclarationNode) {
@@ -132,6 +134,7 @@ public ImportDeclarationSnippet createImportSnippet(Node node) {
         return null;
     }
 
+    @Nullable
     @Override
     public List<VariableDeclarationSnippet> createVariableDeclarationSnippets(Node node) {
         ModuleVariableDeclarationNode dclnNode;
@@ -221,6 +224,7 @@ public List<VariableDeclarationSnippet> createVariableDeclarationSnippets(Node n
         return snippets;
     }
 
+    @Nullable
     @Override
     public ModuleMemberDeclarationSnippet createModuleMemberDeclarationSnippet(Node node)
             throws SnippetException {
@@ -241,6 +245,7 @@ public ModuleMemberDeclarationSnippet createModuleMemberDeclarationSnippet(Node
         return null;
     }
 
+    @Nullable
     @Override
     public StatementSnippet createStatementSnippet(Node node) throws SnippetException {
         if (node instanceof StatementNode) {
@@ -260,6 +265,7 @@ public StatementSnippet createStatementSnippet(Node node) throws SnippetExceptio
         return null;
     }
 
+    @Nullable
     @Override
     public ExpressionSnippet createExpressionSnippet(Node node) {
         if (node instanceof ExpressionNode expressionNode) {

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/utils/ModuleImporter.java

@@ -30,6 +30,7 @@
 import io.ballerina.projects.internal.environment.BallerinaDistribution;
 import io.ballerina.projects.internal.environment.DefaultEnvironment;
 import io.ballerina.shell.Diagnostic;
+import org.jetbrains.annotations.Nullable;
 import org.wso2.ballerinalang.compiler.util.Names;
 
 import java.util.ArrayList;
@@ -79,6 +80,7 @@ public boolean isModuleInDistRepo(String module) {
      * @param module input module.
      * @return import statement.
      */
+    @Nullable
     public String getImportStatement(String module) {
         String importStatement = "import ";
         String langModule = LANG + "." + module;

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/utils/QuotedImport.java

@@ -18,6 +18,8 @@
 
 package io.ballerina.shell.utils;
 
+import org.jetbrains.annotations.Nullable;
+
 import java.util.List;
 import java.util.Objects;
 import java.util.StringJoiner;
@@ -31,7 +33,7 @@ public class QuotedImport {
     private final String orgName;
     private final List<Identifier> moduleNames;
 
-    public QuotedImport(String orgName, List<String> moduleNames) {
+    public QuotedImport(@Nullable String orgName, List<String> moduleNames) {
         this.orgName = orgName;
         this.moduleNames = moduleNames.stream()
                 .map(Identifier::new)

ballerina-shell/modules/shell-core/src/main/java/io/ballerina/shell/utils/StringUtils.java

@@ -24,6 +24,7 @@
 import io.ballerina.tools.text.LinePosition;
 import io.ballerina.tools.text.LineRange;
 import io.ballerina.tools.text.TextDocument;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.StringJoiner;
 import java.util.regex.Matcher;
@@ -152,7 +153,7 @@ public static String encodeIdentifier(String string) {
      * @param object Object to convert.
      * @return Converted string.
      */
-    public static String getExpressionStringValue(Object object) {
+    public static String getExpressionStringValue(@Nullable Object object) {
         return io.ballerina.runtime.api.utils.StringUtils.getExpressionStringValue(object);
     }
 

ballerina-shell/modules/shell-core/src/main/java/module-info.java

@@ -6,6 +6,7 @@
     requires io.ballerina.runtime;
     requires io.ballerina.identifier;
     requires compiler;
+    requires static org.jetbrains.annotations;
 
     exports io.ballerina.shell.exceptions;
     exports io.ballerina.shell.invoker;

ballerina-shell/modules/shell-rt/src/main/java/io/ballerina/shell/rt/InvokerMemory.java

@@ -18,6 +18,8 @@
 
 package io.ballerina.shell.rt;
 
+import org.jetbrains.annotations.Nullable;
+
 import java.util.HashMap;
 
 /**
@@ -44,6 +46,7 @@ private InvokerMemory() {
      * @param name      Name of the variables.
      * @return The value of the variable.
      */
+    @Nullable
     public static Object recall(String contextId, String name) {
         if (memory.containsKey(contextId)) {
             return memory.get(contextId).getOrDefault(quoted(name.trim()), null);

ballerina-shell/modules/shell-rt/src/main/java/module-info.java

@@ -1,3 +1,4 @@
 module io.ballerina.shell.rt {
+    requires static org.jetbrains.annotations;
     exports io.ballerina.shell.rt;
 }