Improve null-safety of cli/spring-boot-cli

See gh-46926

cli/spring-boot-cli/src/main/java/org/springframework/boot/cli/SpringCli.java

@@ -31,6 +31,7 @@ import org.springframework.boot.cli.command.core.HintCommand;
 import org.springframework.boot.cli.command.core.VersionCommand;
 import org.springframework.boot.cli.command.shell.ShellCommand;
 import org.springframework.boot.loader.tools.LogbackInitializer;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.SystemPropertyUtils;
 
@@ -84,7 +85,9 @@ public final class SpringCli {
 		String home = SystemPropertyUtils.resolvePlaceholders("${spring.home:${SPRING_HOME:.}}");
 		File extDirectory = new File(new File(home, "lib"), "ext");
 		if (extDirectory.isDirectory()) {
-			for (File file : extDirectory.listFiles()) {
+			File[] files = extDirectory.listFiles();
+			Assert.state(files != null, "'files' must not be null");
+			for (File file : files) {
 				if (file.getName().endsWith(".jar")) {
 					try {
 						urls.add(file.toURI().toURL());

cli/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/init/ProjectGenerator.java

@@ -98,7 +98,9 @@ class ProjectGenerator {
 		if (!outputDirectory.exists()) {
 			outputDirectory.mkdirs();
 		}
-		try (ZipInputStream zipStream = new ZipInputStream(new ByteArrayInputStream(entity.getContent()))) {
+		byte[] content = entity.getContent();
+		Assert.state(content != null, "'content' must not be null");
+		try (ZipInputStream zipStream = new ZipInputStream(new ByteArrayInputStream(content))) {
 			extractFromStream(zipStream, overwrite, outputDirectory);
 			fixExecutableFlag(outputDirectory, "mvnw");
 			fixExecutableFlag(outputDirectory, "gradlew");

cli/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/shell/RunProcessCommand.java

@@ -52,8 +52,9 @@ class RunProcessCommand extends AbstractCommand {
 	}
 
 	protected ExitStatus run(Collection<String> args) throws IOException {
-		this.process = new RunProcess(this.command);
-		int code = this.process.run(true, StringUtils.toStringArray(args));
+		RunProcess process = new RunProcess(this.command);
+		this.process = process;
+		int code = process.run(true, StringUtils.toStringArray(args));
 		if (code == 0) {
 			return ExitStatus.OK;
 		}
@@ -63,8 +64,9 @@ class RunProcessCommand extends AbstractCommand {
 	}
 
 	boolean handleSigInt() {
-		Assert.state(this.process != null, "'process' must not be null");
-		return this.process.handleSigInt();
+		RunProcess process = this.process;
+		Assert.state(process != null, "'process' must not be null");
+		return process.handleSigInt();
 	}
 
 }