Override available() in RandomAccessDataFile's InputStream

See gh-29295

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/data/RandomAccessDataFile.java

@@ -180,6 +180,11 @@ public class RandomAccessDataFile implements RandomAccessData {
 			return (n <= 0) ? 0 : moveOn(cap(n));
 		}
 
+		@Override
+		public int available() throws IOException {
+			return (int) RandomAccessDataFile.this.length - this.position;
+		}
+
 		/**
 		 * Cap the specified value such that it cannot exceed the number of bytes
 		 * remaining.