some more extensions for PDU impl

src/cfdp/mod.rs

@@ -134,6 +134,12 @@ pub enum ChecksumType {
     NullChecksum = 15,
 }
 
+impl Default for ChecksumType {
+    fn default() -> Self {
+        Self::NullChecksum
+    }
+}
+
 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]

src/cfdp/pdu/metadata.rs

@@ -11,7 +11,7 @@ use alloc::vec::Vec;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct MetadataGenericParams {
     pub closure_requested: bool,

src/cfdp/pdu/mod.rs

@@ -232,7 +232,8 @@ impl CommonPduConfig {
             LargeFileFlag::Normal,
             CrcFlag::NoCrc,
             Direction::TowardsReceiver,
-        ).unwrap()
+        )
+        .unwrap()
     }
 
     pub fn source_id(&self) -> UnsignedByteField {