GROOVY-11874: add null check

Author: eric-milles

src/main/java/groovy/lang/MetaClassImpl.java

@@ -112,7 +112,6 @@
 import java.util.function.BiConsumer;
 
 import static groovy.lang.Tuple.tuple;
-import static java.lang.Character.isUpperCase;
 import static org.apache.groovy.ast.tools.ClassNodeUtils.isValidAccessorName;
 import static org.apache.groovy.util.Arrays.concat;
 import static org.codehaus.groovy.ast.tools.GeneralUtils.inSamePackage;
@@ -2170,7 +2169,9 @@ private Tuple2<MetaMethod, MetaProperty> createMetaMethodAndMetaProperty(final C
         MetaMethod   mm = null;
         MetaProperty mp = getMetaProperty(sender, name, useSuper, isStatic);
 
-        if ((mp == null || mp instanceof CachedField) && !name.isEmpty() && isUpperCase(name.charAt(0)) && (name.length() < 2 || !isUpperCase(name.charAt(1))) && !"Class".equals(name) && !"MetaClass".equals(name)) {
+        if ((mp == null || mp instanceof CachedField)
+                && name != null && !name.isEmpty() && Character.isUpperCase(name.charAt(0)) // GROOVY-11874
+                && (name.length() == 1 || (!Character.isUpperCase(name.charAt(1)) && !name.equals("Class") && !name.equals("MetaClass"))) ) {
             // GROOVY-9618: adjust because capitalised properties aren't stored as meta bean props
             MetaProperty saved = mp;
             mp = getMetaProperty(sender, BeanUtils.decapitalize(name), useSuper, isStatic);

src/test/groovy/groovy/transform/stc/ArraysAndCollectionsSTCTest.groovy

@@ -1073,6 +1073,16 @@ class ArraysAndCollectionsSTCTest extends StaticTypeCheckingTestCase {
         '''
     }
 
+    // GROOVY-11874
+    @Test
+    void testMapGetAt() {
+        assertScript '''
+            String name = null
+            def map = [:]
+            map[name]
+        '''
+    }
+
     // GROOVY-6266
     @Test
     void testMapGenerics() {