build(checkstyle): introduce team Checkstyle config and enforce build failure on violations

- Add src/test/resources/team/checkstyle-rules.xml: tab-based indentation
  (Indentation module, basicOffset=4), import ordering with JDK/third-party/
  internal groups, relaxed ParameterNumber and VisibilityModifier disabled
- Switch pom.xml configLocation from google_checks.xml to team config,
  set failOnViolation=true, add logViolationsToConsole and
  includeTestSourceDirectory, cover both src/main and src/test
- Extend .editorconfig and ensure it cooperates with Checkstyle
- Fix all resulting Checkstyle violations across the codebase:
  import ordering, NeedBraces, FinalClass/HideUtilityClassConstructor,
  EqualsAvoidNull, ModifierOrder, CatchParameterName, etc.

Author: spannm

.editorconfig

@@ -1,13 +1,21 @@
-# EditorConfig: http://EditorConfig.org
+# EditorConfig — https://editorconfig.org
 root = true
 
+# ── Defaults for all files ────────────────────────────────────────────────────
 [*]
-indent_style = tab
-indent_size = 4
-end_of_line = lf
-charset = utf-8
+indent_style             = tab
+indent_size              = 4
+end_of_line              = lf
+charset                  = utf-8
 trim_trailing_whitespace = true
-insert_final_newline = true
+insert_final_newline     = true
 
+# ── Markdown ──────────────────────────────────────────────────────────────────
+# Trailing spaces are significant in Markdown (line break); keep them.
 [*.md]
 trim_trailing_whitespace = false
+max_line_length          = off
+
+# ── Shell scripts ─────────────────────────────────────────────────────────────
+[*.sh]
+indent_size = 2

pom.xml

@@ -316,16 +316,15 @@
 				<artifactId>maven-checkstyle-plugin</artifactId>
 				<version>${dep.plugin.checkstyle.version}</version>
 				<configuration>
-					<configLocation>google_checks.xml</configLocation>
+					<configLocation>${project.basedir}/src/test/resources/team/checkstyle-rules.xml</configLocation>
 					<consoleOutput>true</consoleOutput>
-					<failOnViolation>false</failOnViolation>
-					<sourceDirectories>
-						<sourceDirectory>${project.basedir}/src/main/java</sourceDirectory>
-					</sourceDirectories>
+					<failOnViolation>true</failOnViolation>
+					<includeTestSourceDirectory>true</includeTestSourceDirectory>
+					<logViolationsToConsole>true</logViolationsToConsole>
 				</configuration>
 				<executions>
 					<execution>
-						<id>checkstyle</id>
+						<id>checkstyle-check</id>
 						<phase>verify</phase>
 						<goals>
 							<goal>check</goal>

src/main/java/com/devskiller/jfairy/Bootstrap.java

@@ -43,22 +43,25 @@
  * @author Jakub Kubrynski
  * @author Olga Maciaszek-Sharma
  */
-public class Bootstrap {
+public final class Bootstrap {
 
 	private static final Logger LOG = LoggerFactory.getLogger(Bootstrap.class);
 
 	private static final String DATA_FILE_PREFIX = "jfairy";
 
+	private Bootstrap() {
+	}
+
 	public static Fairy createFairy(DataMaster dataMaster, Locale locale, RandomGenerator randomGenerator) {
 		// Create base components
 		BaseProducer baseProducer = new BaseProducer(randomGenerator);
 		TimeProvider timeProvider = new TimeProvider();
 		DateProducer dateProducer = new DateProducer(baseProducer, timeProvider);
-		
+
 		// Create locale-specific providers
 		LocaleSpecificProviders localeProviders = LocaleSpecificProvidersFactory.createProvidersForLocale(
 				locale, dataMaster, baseProducer, dateProducer);
-		
+
 		// Create company factory first (needed by PersonFactory)
 		CompanyFactory companyFactory = new CompanyFactoryImpl(
 				baseProducer, dataMaster, localeProviders.vatIdentificationNumberProvider()
@@ -74,31 +77,30 @@ public static Fairy createFairy(DataMaster dataMaster, Locale locale, RandomGene
 				timeProvider,
 				companyFactory
 		);
-		
+
 		IBANFactory ibanFactory = new IBANFactoryImpl(baseProducer, dataMaster);
-		
+
 		// Create other producers
 		CreditCardProvider creditCardProvider = new CreditCardProvider(dataMaster, baseProducer, dateProducer);
 		TextProducerInternal textProducerInternal = new TextProducerInternal(dataMaster, baseProducer);
 		IPNumberProducer ipNumberProducer = new IPNumberProducer(baseProducer);
-		
+
 		// Create fairy factory
 		FairyFactory fairyFactory = new FairyFactoryImpl(
 				textProducerInternal, baseProducer, personFactory,
 				ipNumberProducer, dateProducer, creditCardProvider,
 				companyFactory, ibanFactory
 		);
-		
+
 		return fairyFactory.createFairy();
 	}
 
-
 	private static void fillDefaultDataMaster(MapBasedDataMaster dataMaster, Locale locale, String filePrefix) {
 		try {
 			dataMaster.readResources(filePrefix + ".yml");
 			dataMaster.readResources(filePrefix + "_" + locale.getLanguage() + ".yml");
-		} catch (IOException e) {
-			throw new IllegalStateException(e);
+		} catch (IOException ex) {
+			throw new IllegalStateException(ex);
 		}
 	}
 
@@ -111,7 +113,6 @@ public static Builder builder() {
 		return new Builder();
 	}
 
-
 	/**
 	 * Use this factory method to create dataset containing default jfairy.yml and jfairy_{langCode}.yml files
 	 * merged with custom files with the same name
@@ -146,20 +147,17 @@ public static Fairy create(Locale locale, String dataFilePrefix) {
 				.build();
 	}
 
-
 	public static Fairy create(Supplier<DataMaster> dataMaster, Locale locale) {
 		return builder().withDataMasterProvider(dataMaster).withLocale(locale).build();
 	}
 
-	
-	public static class Builder {
+	public static final class Builder {
 
 		private Locale locale = Locale.ENGLISH;
 		private String filePrefix = DATA_FILE_PREFIX;
 		private RandomGenerator randomGenerator = new RandomGenerator();
 		private DataMaster dataMaster;
 
-
 		private MapBasedDataMaster getDefaultDataMaster(BaseProducer baseProducer) {
 			return new MapBasedDataMaster(baseProducer);
 		}
@@ -213,7 +211,6 @@ public Builder withDataMasterProvider(Supplier<DataMaster> dataMasterProvider) {
 			return this;
 		}
 
-
 		/**
 		 * Returns the completed Fairy.
 		 *
@@ -229,5 +226,4 @@ public Fairy build() {
 		}
 	}
 
-
 }

src/main/java/com/devskiller/jfairy/Fairy.java

@@ -59,7 +59,6 @@ public static Fairy create(Supplier<DataMaster> dataMasterProvider, Locale local
 		return Bootstrap.create(dataMasterProvider, locale);
 	}
 
-
 	public static Bootstrap.Builder builder() {
 		return Bootstrap.builder();
 	}

src/main/java/com/devskiller/jfairy/FairyFactoryImpl.java

@@ -44,8 +44,8 @@ class FairyFactoryImpl implements FairyFactory {
 	public Fairy createFairy() {
 		TextProducer textProducer = new TextProducer(textProducerInternal, baseProducer);
 		NetworkProducer networkProducer = new NetworkProducer(ipNumberProducer);
-		
-		return new Fairy(textProducer, personFactory, networkProducer, baseProducer, 
+
+		return new Fairy(textProducer, personFactory, networkProducer, baseProducer,
 		                 dateProducer, creditCardProvider, companyFactory, ibanFactory);
 	}
 }

src/main/java/com/devskiller/jfairy/LocaleSpecificProvidersFactory.java

@@ -8,54 +8,54 @@
 import com.devskiller.jfairy.data.DataMaster;
 import com.devskiller.jfairy.producer.BaseProducer;
 import com.devskiller.jfairy.producer.DateProducer;
+import com.devskiller.jfairy.producer.company.locale.br.BrVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.de.DeVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.en.EnVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.es.EsVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.ka.KaVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.pl.PlVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.sk.SkVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.sv.SvVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.company.locale.zh.ZhVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.NationalIdentificationNumberFactory;
 import com.devskiller.jfairy.producer.person.locale.NoNationalIdentificationNumberFactory;
+import com.devskiller.jfairy.producer.person.locale.br.BrAddressProvider;
+import com.devskiller.jfairy.producer.person.locale.br.BrNationalIdentityCardNumberProvider;
+import com.devskiller.jfairy.producer.person.locale.br.BrPassportNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.de.DeAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.de.DeNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.de.DePassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.de.DeVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.en.EnAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.en.EnNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.en.EnPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.en.EnVATIdentificationNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.br.BrVATIdentificationNumberProvider;
-import com.devskiller.jfairy.producer.person.locale.br.BrAddressProvider;
-import com.devskiller.jfairy.producer.person.locale.br.BrNationalIdentityCardNumberProvider;
-import com.devskiller.jfairy.producer.person.locale.br.BrPassportNumberProvider;
-import com.devskiller.jfairy.producer.person.locale.fr.FrAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.es.EsAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.es.EsNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.es.EsPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.es.EsVATIdentificationNumberProvider;
+import com.devskiller.jfairy.producer.person.locale.fr.FrAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.ka.KaAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.ka.KaNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.ka.KaPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.ka.KaVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.pl.PlAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.pl.PlNationalIdentificationNumberFactory;
 import com.devskiller.jfairy.producer.person.locale.pl.PlNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.pl.PlPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.pl.PlVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.sk.SkAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.sk.SkNationalIdentificationNumberFactory;
 import com.devskiller.jfairy.producer.person.locale.sk.SkNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.sk.SkPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.sk.SkVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.sv.SvAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.sv.SvNationalIdentificationNumberFactory;
 import com.devskiller.jfairy.producer.person.locale.sv.SvNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.sv.SvPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.sv.SvVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.zh.ZhAddressProvider;
 import com.devskiller.jfairy.producer.person.locale.zh.ZhNationalIdentityCardNumberProvider;
 import com.devskiller.jfairy.producer.person.locale.zh.ZhPassportNumberProvider;
-import com.devskiller.jfairy.producer.company.locale.zh.ZhVATIdentificationNumberProvider;
 import com.devskiller.jfairy.producer.util.LanguageCode;
 
 /**
  * Factory for creating locale-specific provider implementations
  */
-class LocaleSpecificProvidersFactory {
+final class LocaleSpecificProvidersFactory {
 
 	private static final Logger LOG = LoggerFactory.getLogger(LocaleSpecificProvidersFactory.class);
 
@@ -69,7 +69,7 @@ static LocaleSpecificProviders createProvidersForLocale(Locale locale,
 		LanguageCode code;
 		try {
 			code = LanguageCode.valueOf(locale.getLanguage().toUpperCase());
-		} catch (IllegalArgumentException e) {
+		} catch (IllegalArgumentException ex) {
 			LOG.warn("Unknown locale {}", locale);
 			code = LanguageCode.EN;
 		}

src/main/java/com/devskiller/jfairy/data/DataMaster.java

@@ -14,11 +14,10 @@ public interface DataMaster {
 
 	List<String> getStringList(String key);
 
-	<T> T getValuesOfType(String dataKey, final String type, final Class<T> resultClass);
+	<T> T getValuesOfType(String dataKey, String type, Class<T> resultClass);
 
 	String getRandomValue(String key);
 
 	LanguageCode getLanguage();
 
-
 }

src/main/java/com/devskiller/jfairy/data/MapBasedDataMaster.java

@@ -19,14 +19,12 @@
 import com.devskiller.jfairy.producer.util.LanguageCode;
 import com.devskiller.jfairy.producer.util.ValidateUtils;
 
-
 public class MapBasedDataMaster implements DataMaster {
 
 	public static final String LANGUAGE_TAG = "language";
 	private final BaseProducer baseProducer;
 	private Map<String, Object> dataSource = new CaseInsensitiveMap();
 
-
 	public MapBasedDataMaster(BaseProducer baseProducer) {
 		this.baseProducer = baseProducer;
 	}
@@ -119,7 +117,7 @@ private void appendData(Map<String, Object> data) {
 		dataSource.putAll(data);
 	}
 
-	private static class CaseInsensitiveMap extends HashMap<String, Object> {
+	private static final class CaseInsensitiveMap extends HashMap<String, Object> {
 
 		@Override
 		@SuppressWarnings("unchecked")

src/main/java/com/devskiller/jfairy/package-info.java

@@ -1,3 +1,12 @@
+/**
+ * Core package of the jFairy library.
+ * <p>
+ * This package contains the main entry points for the library, such as the {@link com.devskiller.jfairy.Fairy}
+ * facade and the {@link com.devskiller.jfairy.Bootstrap} class for initialization.
+ * <p>
+ * The {@link com.devskiller.jfairy.FairyFactory} provides mechanisms to create localized instances
+ * of the data generators.
+ */
 @NullMarked
 package com.devskiller.jfairy;
 

src/main/java/com/devskiller/jfairy/producer/BaseProducer.java

@@ -8,7 +8,6 @@ public class BaseProducer {
 
 	private final RandomGenerator random;
 
-
 	public BaseProducer(RandomGenerator random) {
 		this.random = random;
 	}
@@ -80,8 +79,6 @@ private <T> List<T> extractRandomList(List<T> elements, int count) {
 		return elements.subList(0, count);
 	}
 
-
-
 	/**
 	 * Returns random int value
 	 *