#1524 replaced java.beans.Introspector with a custom IntrospectorUtils class to avoid java.desktop module

documentation/src/main/asciidoc/mapstruct-reference-guide.asciidoc

@@ -2757,7 +2757,7 @@ public class CustomAccessorNamingStrategy extends DefaultAccessorNamingStrategy
     @Override
     public String getPropertyName(ExecutableElement getterOrSetterMethod) {
         String methodName = getterOrSetterMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.startsWith( "with" ) ? methodName.substring(  4 ) : methodName );
+        return IntrospectorUtils.decapitalize( methodName.startsWith( "with" ) ? methodName.substring(  4 ) : methodName );
     }
 }
 ----

integrationtest/src/test/resources/namingStrategyTest/strategy/src/main/java/org/mapstruct/itest/naming/CustomAccessorNamingStrategy.java

@@ -5,13 +5,12 @@
  */
 package org.mapstruct.itest.naming;
 
-import java.beans.Introspector;
-
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.type.TypeKind;
 
 import org.mapstruct.ap.spi.AccessorNamingStrategy;
 import org.mapstruct.ap.spi.DefaultAccessorNamingStrategy;
+import org.mapstruct.ap.spi.util.IntrospectorUtils;
 
 /**
  * A custom {@link AccessorNamingStrategy} recognizing getters in the form of {@code property()} and setters in the
@@ -42,13 +41,14 @@ public class CustomAccessorNamingStrategy  extends DefaultAccessorNamingStrategy
     @Override
     public String getPropertyName(ExecutableElement getterOrSetterMethod) {
         String methodName = getterOrSetterMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.startsWith( "with" ) ? methodName.substring(  4 ) : methodName );
+        return IntrospectorUtils.decapitalize(
+            methodName.startsWith( "with" ) ? methodName.substring( 4 ) : methodName );
     }
 
     @Override
     public String getElementName(ExecutableElement adderMethod) {
         String methodName = adderMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.substring( 3 ) );
+        return IntrospectorUtils.decapitalize( methodName.substring( 3 ) );
     }
 
 }

processor/src/main/java/org/mapstruct/ap/spi/DefaultAccessorNamingStrategy.java

@@ -5,7 +5,6 @@
  */
 package org.mapstruct.ap.spi;
 
-import java.beans.Introspector;
 import java.util.regex.Pattern;
 
 import javax.lang.model.element.ExecutableElement;
@@ -16,6 +15,7 @@ import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.SimpleElementVisitor6;
 import javax.lang.model.util.SimpleTypeVisitor6;
 
+import org.mapstruct.ap.spi.util.IntrospectorUtils;
 
 /**
  * The default JavaBeans-compliant implementation of the {@link AccessorNamingStrategy} service provider interface.
@@ -157,12 +157,12 @@ public class DefaultAccessorNamingStrategy implements AccessorNamingStrategy {
     public String getPropertyName(ExecutableElement getterOrSetterMethod) {
         String methodName = getterOrSetterMethod.getSimpleName().toString();
         if ( methodName.startsWith( "is" ) || methodName.startsWith( "get" ) || methodName.startsWith( "set" ) ) {
-            return Introspector.decapitalize( methodName.substring( methodName.startsWith( "is" ) ? 2 : 3 ) );
+            return IntrospectorUtils.decapitalize( methodName.substring( methodName.startsWith( "is" ) ? 2 : 3 ) );
         }
         else if ( isBuilderSetter( getterOrSetterMethod ) ) {
             return methodName;
         }
-        return Introspector.decapitalize( methodName.substring( methodName.startsWith( "is" ) ? 2 : 3 ) );
+        return IntrospectorUtils.decapitalize( methodName.substring( methodName.startsWith( "is" ) ? 2 : 3 ) );
     }
 
     /**
@@ -177,10 +177,10 @@ public class DefaultAccessorNamingStrategy implements AccessorNamingStrategy {
     @Override
     public String getElementName(ExecutableElement adderMethod) {
         String methodName = adderMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.substring( 3 ) );
+        return IntrospectorUtils.decapitalize( methodName.substring( 3 ) );
     }
 
-   /**
+    /**
      * Helper method, to obtain the fully qualified name of a type.
      *
      * @param type input type

processor/src/main/java/org/mapstruct/ap/spi/util/IntrospectorUtils.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.spi.util;
+
+/**
+ * Utilities for tools to learn about the properties, events, and methods supported by a target Java Bean.
+ * It is mainly needed to avoid using {@link java.beans.Introspector} class which is part of java.desktop module
+ * from java 9, thus avoiding pulling a module ( of around 10 MB ) for using a single class.
+ *
+ * @author Saheb Preet Singh
+ */
+public class IntrospectorUtils {
+
+    private IntrospectorUtils() {
+    }
+
+    /**
+     * Utility method to take a string and convert it to normal Java variable
+     * name capitalization.  This normally means converting the first
+     * character from upper case to lower case, but in the (unusual) special
+     * case when there is more than one character and both the first and
+     * second characters are upper case, we leave it alone.
+     * <p>
+     * Thus "FooBah" becomes "fooBah" and "X" becomes "x", but "URL" stays
+     * as "URL".
+     *
+     * @param name The string to be decapitalized.
+     *
+     * @return The decapitalized version of the string.
+     */
+    public static String decapitalize(String name) {
+        if ( name == null || name.length() == 0 ) {
+            return name;
+        }
+        if ( name.length() > 1 && Character.isUpperCase( name.charAt( 1 ) ) &&
+            Character.isUpperCase( name.charAt( 0 ) ) ) {
+            return name;
+        }
+        char[] chars = name.toCharArray();
+        chars[0] = Character.toLowerCase( chars[0] );
+        return new String( chars );
+    }
+
+}

processor/src/main/java/org/mapstruct/ap/spi/util/package-info.java

@@ -0,0 +1,7 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+
+package org.mapstruct.ap.spi.util;

processor/src/test/java/org/mapstruct/ap/spi/util/IntrospectorUtilsTest.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.spi.util;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+/**
+ * @author Saheb Preet Singh
+ */
+public class IntrospectorUtilsTest {
+
+    @Test
+    public void testDecapitalize() throws Exception {
+        assertThat( IntrospectorUtils.decapitalize( null ) ).isNull();
+        assertThat( IntrospectorUtils.decapitalize( "" ) ).isEqualTo( "" );
+        assertThat( IntrospectorUtils.decapitalize( "URL" ) ).isEqualTo( "URL" );
+        assertThat( IntrospectorUtils.decapitalize( "FooBar" ) ).isEqualTo( "fooBar" );
+        assertThat( IntrospectorUtils.decapitalize( "PArtialCapitalized" ) ).isEqualTo( "PArtialCapitalized" );
+        assertThat( IntrospectorUtils.decapitalize( "notCapitalized" ) ).isEqualTo( "notCapitalized" );
+        assertThat( IntrospectorUtils.decapitalize( "a" ) ).isEqualTo( "a" );
+    }
+
+}

processor/src/test/java/org/mapstruct/ap/test/naming/spi/CustomAccessorNamingStrategy.java

@@ -5,11 +5,10 @@
  */
 package org.mapstruct.ap.test.naming.spi;
 
-import java.beans.Introspector;
-
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.type.TypeKind;
 
+import org.mapstruct.ap.spi.util.IntrospectorUtils;
 import org.mapstruct.ap.spi.AccessorNamingStrategy;
 import org.mapstruct.ap.spi.DefaultAccessorNamingStrategy;
 
@@ -42,13 +41,14 @@ public class CustomAccessorNamingStrategy extends DefaultAccessorNamingStrategy
     @Override
     public String getPropertyName(ExecutableElement getterOrSetterMethod) {
         String methodName = getterOrSetterMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.startsWith( "with" ) ? methodName.substring(  4 ) : methodName );
+        return IntrospectorUtils.decapitalize(
+            methodName.startsWith( "with" ) ? methodName.substring( 4 ) : methodName );
     }
 
     @Override
     public String getElementName(ExecutableElement adderMethod) {
         String methodName = adderMethod.getSimpleName().toString();
-        return Introspector.decapitalize( methodName.substring( 3 ) );
+        return IntrospectorUtils.decapitalize( methodName.substring( 3 ) );
     }
 
 }