CAMEL-23378: avoid String to InputStream conversion

Author: mcarlett

core/camel-spring-boot/src/main/java/org/apache/camel/spring/boot/SpringTypeConverter.java

@@ -16,6 +16,7 @@
  */
 package org.apache.camel.spring.boot;
 
+import java.io.InputStream;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -52,6 +53,13 @@ public <T> T convertTo(Class<T> type, Exchange exchange, Object value) throws Ty
             return null;
         }
 
+        // do not attempt to convert String -> InputStream (or subclasses like FileInputStream).
+        // Spring's ObjectToObjectConverter finds FileInputStream(String) constructor and treats
+        // the String value as a file path instead of data content.
+        if (value instanceof String && InputStream.class.isAssignableFrom(type)) {
+            return null;
+        }
+
         TypeDescriptor sourceType = types.computeIfAbsent(value.getClass(), TypeDescriptor::valueOf);
         TypeDescriptor targetType = types.computeIfAbsent(type, TypeDescriptor::valueOf);
 

core/camel-spring-boot/src/test/java/org/apache/camel/spring/boot/SpringTypeConverterTest.java

@@ -16,6 +16,8 @@
  */
 package org.apache.camel.spring.boot;
 
+import java.io.FileInputStream;
+import java.io.InputStream;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
@@ -70,6 +72,19 @@ public void testConversionService() {
         Assertions.assertNull(converter.convertTo(String.class, source));
     }
 
+    @Test
+    public void testStringToFileInputStreamConversionIsBlocked() {
+        // Spring's ObjectToObjectConverter sees FileInputStream(String) constructor and
+        // treats String content as a file path — must return null so Camel's own converters
+        // handle String -> InputStream correctly
+        Assertions.assertNull(converter.convertTo(FileInputStream.class, null, "some file content"));
+    }
+
+    @Test
+    public void testStringToInputStreamConversionIsBlocked() {
+        Assertions.assertNull(converter.convertTo(InputStream.class, null, "some file content"));
+    }
+
     public static class Person {
         private String name;
         private int age;