Remove unused inner class (#10958)

Author: elharo

compat/maven-builder-support/src/test/java/org/apache/maven/building/ProblemCollectorFactoryTest.java

@@ -40,72 +40,6 @@ void testNewInstance() {
         assertEquals(1, collector2.getProblems().size());
     }
 
-    private static class TestProblem implements Problem {
-        private final String message;
-        private final Problem.Severity severity;
-        private final String source;
-        private final int lineNumber;
-        private final int columnNumber;
-        private final Exception cause;
-
-        TestProblem(
-                String message,
-                Problem.Severity severity,
-                String source,
-                int lineNumber,
-                int columnNumber,
-                Exception cause) {
-            this.message = message;
-            this.severity = severity;
-            this.source = source != null ? source : "";
-            this.lineNumber = lineNumber;
-            this.columnNumber = columnNumber;
-            this.cause = cause;
-        }
-
-        @Override
-        public String getSource() {
-            return source;
-        }
-
-        @Override
-        public int getLineNumber() {
-            return lineNumber;
-        }
-
-        @Override
-        public int getColumnNumber() {
-            return columnNumber;
-        }
-
-        @Override
-        public String getLocation() {
-            final StringBuilder loc = new StringBuilder(source);
-            if (lineNumber > 0) {
-                loc.append(":").append(lineNumber);
-                if (columnNumber > 0) {
-                    loc.append(":").append(columnNumber);
-                }
-            }
-            return loc.toString();
-        }
-
-        @Override
-        public String getMessage() {
-            return message;
-        }
-
-        @Override
-        public Exception getException() {
-            return cause;
-        }
-
-        @Override
-        public Problem.Severity getSeverity() {
-            return severity;
-        }
-    }
-
     @Test
     void testAddProblem() {
         ProblemCollector collector = ProblemCollectorFactory.newInstance(null);